Objectives. Platelet-rich plasma (PRP) is being used increasingly often in the clinical setting to treat tendon-related pathologies. Yet the optimal PRP preparations to promote tendon healing in different patient populations are poorly defined. Here, we sought to determine whether increasing the concentration of platelet-derived proteins within a derivative of PRP, platelet lysate (PL), enhances tenocyte proliferation and migration in vitro, and whether the mitogenic properties of PL change with donor age. Methods. Concentrated PLs from both young (< 50 years) and aged (> 50 years) donors were prepared by exposing pooled PRP to a series of freeze-thaw cycles followed by dilution in plasma, and the levels of several platelet-derived proteins were measured using multiplex immunoassay technology. Human tenocytes were cultured with PLs to simulate a clinically relevant PRP treatment range, and cell growth and migration were assessed using DNA quantitation and gap closure assays, respectively. Results. Platelet-derived protein levels increased alongside higher PL concentrations, and PLs from both age groups improved tenocyte proliferation relative to control conditions. However, PLs from aged donors yielded a dose-response relationship in tenocyte behaviour, with higher PL concentrations resulting in increased tenocyte proliferation and migration. Conversely, no significant differences in tenocyte behaviour were detected when increasing the concentration of PLs from younger donors. Conclusion. Higher PL concentrations, when prepared from the PRP of aged but not young donors, were more effective than lower PL concentrations at promoting tenocyte proliferation and migration in vitro. Cite this article: D. R. Berger, C. J. Centeno, N. J. Steinmetz. Platelet lysates from aged donors promote human tenocyte proliferation and migration in a concentration-dependent manner. Bone Joint Res 2019;8:32–40. DOI: 10.1302/2046-3758.81.BJR-2018-0164.R1

Objective. Early cell loss of up to 50% is common to in vitro chondrogenesis of mesenchymal stromal cells (MSC) and stimulation of cell proliferation could compensate for this unwanted effect and improve efficacy and tissue yield for cartilage tissue engineering. We recently demonstrated that proliferation is an essential requirement for successful chondrogenesis of MSC, however, how it is regulated is still completely unknown. We therefore aimed to identify signaling pathways involved in the regulation of proliferation during in vitro chondrogenesis and investigated, whether activation of relevant pathways could stimulate proliferation. Design. Human MSC were subjected to in vitro chondrogenesis for up to 42 days under standard conditions in the presence of 10 ng/ml TGF-β. Cells were or were not additionally treated with inhibitors of bone morphogenetic protein (BMP), insulin-like growth factor (IGF) IGF/PI3K, fibroblast growth factor (FGF) or indian hedgehog (IHH) pathways for two or four weeks. To investigate the stimulation of proliferation by exogenous factors, cells were treated with BMP-4, IGF-1, FGF-18 or purmorphamine (small molecule hedgehog agonist). Proliferation was determined by [3H]-thymidine incorporation. Results and Discussion. Quantitative assessment of proliferation revealed that proliferation arrest occurred during condensation up to day 3 and cell division was re-initiated thereafter with a peak on day 28. To test which pathways are relevant for the restart of proliferation, BMP, IGF/PI3K, FGF or IHH signaling was inhibited up to day 14. All treatments significantly reduced proliferation > 50% and, thus, seemed to participate in the re-entry into the cell cycle. To study whether the same pathways are relevant to maintain cells in a proliferative state later on, inhibitors were supplemented from day 14–28. This resulted in a significant decrease of proliferation in the groups treated with inhibitors of BMP (67% decrease), FGF (70%) and IHH (30%) signaling, while inhibition of IGF/PI3K did not influence late proliferation. Although BMP-4, IGF-1 or FGF-18 are known mitogenic factors in the growth plate, stimulation of cells by exogenous addition of these factors did not enhance proliferation in any differentiation phase. In contrast, stimulation of IHH signaling from day 14–28 significantly increased proliferation by 44%. This is in line with the documented strong mitogenic activity of hedgehog signaling in the proliferative zone of the growth plate. Thus, our data demonstrated that BMP, IGF/PI3K, FGF and IHH essentially participate in the regulation of proliferation during in vitro chondrogenesis. Early or late activation of single pathways by exogenous factors was, however, not sufficient to increase proliferation significantly with the exception of late activation of hedgehog signaling. Optimization of stimulation of the hedgehog pathway with a focus on increased tissue yield will now be the next step

Objectives. The aim of this study was to investigate the effect of granulocyte-colony stimulating factor (G-CSF) on mesenchymal stem cell (MSC) proliferation in vitro and to determine whether pre-microfracture systemic administration of G-CSF (a bone marrow stimulant) could improve the quality of repaired tissue of a full-thickness cartilage defect in a rabbit model. Methods. MSCs from rabbits were cultured in a control medium and medium with G-CSF (low-dose: 4 μg, high-dose: 40 μg). At one, three, and five days after culturing, cells were counted. Differential potential of cultured cells were examined by stimulating them with a osteogenic, adipogenic and chondrogenic medium. A total of 30 rabbits were divided into three groups. The low-dose group (n = 10) received 10 μg/kg of G-CSF daily, the high-dose group (n = 10) received 50 μg/kg daily by subcutaneous injection for three days prior to creating cartilage defects. The control group (n = 10) was administered saline for three days. At 48 hours after the first injection, a 5.2 mm diameter cylindrical osteochondral defect was created in the femoral trochlea. At four and 12 weeks post-operatively, repaired tissue was evaluated macroscopically and microscopically. Results. The cell count in the low-dose G-CSF medium was significantly higher than that in the control medium. The differentiation potential of MSCs was preserved after culturing them with G-CSF. Macroscopically, defects were filled and surfaces were smoother in the G-CSF groups than in the control group at four weeks. At 12 weeks, the quality of repaired cartilage improved further, and defects were almost completely filled in all groups. Microscopically, at four weeks, defects were partially filled with hyaline-like cartilage in the G-CSF groups. At 12 weeks, defects were repaired with hyaline-like cartilage in all groups. Conclusions. G-CSF promoted proliferation of MSCs in vitro. The systemic administration of G-CSF promoted the repair of damaged cartilage possibly through increasing the number of MSCs in a rabbit model. Cite this article: T. Sasaki, R. Akagi, Y. Akatsu, T. Fukawa, H. Hoshi, Y. Yamamoto, T. Enomoto, Y. Sato, R. Nakagawa, K. Takahashi, S. Yamaguchi, T. Sasho. The effect of systemic administration of G-CSF on a full-thickness cartilage defect in a rabbit model MSC proliferation as presumed mechanism: G-CSF for cartilage repair. Bone Joint Res 2017;6:123–131. DOI: 10.1302/2046-3758.63.BJR-2016-0083

Introduction and Objective. Achilles tendon defect is difficult problem for orthopedic surgeon, and therefore the development of new treatments is desirable. Platelet-rich fibrin (PRF), dense fibrin scaffold composed of a fibrin matrix containing many growth factors, is recently used as regenerative medicine preparation. However, few data are available on the usefulness of PRF on Achilles tendon healing after injury. The objective of this study is to examine whether PRF promotes the healing of Achilles tendon defect in vivo and evaluated the effects of PRF on tenocytes in vitro. Materials and Methods. PRF were prepared from rats according to international guidelines on the literature. To create rat model for Achilles tendon defect, a 4-mm portion of the right Achilles tendon was completely resected, and PRF was placed into the gap in PRF group before sewing the gap with nylon sutures. To assess the histological healing of Achilles tendon defect, Bonar score was calculated using HE, Alcian-blue, and Picosirius-red staining section. Basso, Beattie, Bresnahan (BBB) score was used for the evaluation of motor functional recovery. Biomechanical properties including failure tensile load, ultimate tensile stress, breaking elongation, and elastic modulus were measured. We examined the effects of PRF on tenocytes isolated from rat Achilles tendon in vitro. The number of viable cells were measured by MTS assay, and immunostaining of ki-67 was used for detection of proliferative cells. Migration of tenocytes was evaluated by wound closure assay. Protein or gene expression level of extracellular matrix protein, such as collagen, were evaluated by immunoblotting, immunofluorescence, or PCR. Phosphorylation level of AKT, FGF receptor, or SMAD3 was determined by western blotting. Inhibitory experiments were performed using MK-2206 (AKT inhibitor), FIIN-2 (FGFR inhibitor), SB-431542 (TGF-B receptor inhibitor), or SIS3 (SMAD3 inhibitor). All p values presented are two-sided and p values < 0.05 were considered statistically significant. Results. In rat Achilles tendon defects, Bonar score was significantly improved in PRF group compared to control group. Collagen deposition at the site of Achilles tendon defect was observed earlier in PRF group. Consistent with the histological findings, BBB score was significantly improved in PRF group. PRF also significantly improved the biomechanical properties of injured Achilles tendon. Furthermore, proliferating tenocytes, labelled by ki-67 were significantly increased in PRF group. These data suggested PRF prompted the healing of Achilles tendon defect. Thus, we further examined the effects of PRF on tenocytes in vitro. PRF significantly increased the number of viable cells, the proliferative cells labelled by ki-67, and migratory ability. Furthermore, PRF significantly increased the protein expression levels of collagen-I, collagen-III, α-SMA, and tenascin-C in tenocytes. Next, we examined the signalling pathway associated with PRF-induced proliferation of tenocytes. PRF increased the phosphorylation level and induced nuclear translocation of AKT, known as key regulator of cell survival. PRF also induced the phosphorylation of FGF receptor. Inhibition of AKT or FGF-receptor completely suppressed the positive effects of PRF on tenocytes. Furthermore, we found that inhibition of FGF receptor partially suppressed the phosphorylation of AKT by PRF. Thus, PRF induced the proliferation of tenocytes via FGFR/AKT axis. We further evaluated the signalling pathway associated with PRF-induced expression of extracellular matrix. PRF increased the phosphorylation levels of SMAD3 and induced nuclear translocation of SMAD3. Furthermore, inhibition of TGF-B receptor or SMAD3 suppressed increased expression level of extracellular matrix by PRF. Thus, PRF increased expression level of extracellular matrix protein via TGF-BR/SMAD3 axis. Conclusions. PRF promotes tendon healing of the Achilles tendon defect and recovery of exercise performance and biomechanical properties. PRF increases the proliferation ability or protein expression level of extracellular matrix protein in tenocytes via FGFR/AKT or TGF-βR/SMAD3 axis, respectively

Colchicine is often used in the treatment of diseases such as familial Mediterranean fever (FMF) and gout. We have previously reported that patients with FMF who had colchicine on a daily basis and who had a total hip arthroplasty showed no heterotopic ossification after surgery. The mechanism by which colchicine causes this clinical phenomenon has never been elucidated. We therefore evaluated the effect of various concentrations of colchicine on cell proliferation and mineralisation in tissue culture, using rat and human cells with and without osteogenic potential. Cell proliferation was assessed by direct cell counts and uptake of (. 3. H)thymidine, and mineralisation by measuring the amount of staining by Alizarin Red. Our findings indicate that concentrations of colchicine of up to 3 ng/ml did not affect cell proliferation but inhibition was observed at 10 to 30 ng/ml. Mineralisation decreased to almost 50%, which was the maximum inhibition observed, at concentrations of colchicine of 2.5 ng/ml. These results indicate that colchicine at low concentrations, of up to 3 ng/ml, has the capacity to inhibit selectively bone-like cell mineralisation in culture, without affecting cell proliferation. Further clinical and laboratory studies are necessary to evaluate the effects of colchicine on biological processes involving the proliferation of osteoblasts and tissue mineralisation in vivo, such as the healing of fractures, the formation of heterotopic bone and neoplastic bone growth

Human articular cartilage samples were retrieved from the resected material of patients undergoing total knee replacement. Samples underwent automated controlled freezing at various stages of preparation: as intact articular cartilage discs, as minced articular cartilage, and as chondrocytes immediately after enzymatic isolation from fresh articular cartilage. Cell viability was examined using a LIVE/DEAD assay which provided fluorescent staining. Isolated chondrocytes were then cultured and Alamar blue assay was used for estimation of cell proliferation at days zero, four, seven, 14, 21 and 28 after seeding. The mean percentage viabilities of chondrocytes isolated from group A (fresh, intact articular cartilage disc samples), group B (following cryopreservation and then thawing, after initial isolation from articular cartilage), group C (from minced cryopreserved articular cartilage samples), and group D (from cryopreserved intact articular cartilage disc samples) were 74.7% (95% confidence interval (CI) 73.1 to 76.3), 47.0% (95% CI 43 to 51), 32.0% (95% CI 30.3 to 33.7) and 23.3% (95% CI 22.1 to 24.5), respectively. Isolated chondrocytes from all groups were expanded by the following mean proportions after 28 days of culturing: group A ten times, group B 18 times, group C 106 times, and group D 154 times. This experiment demonstrated that it is possible to isolate viable chondrocytes from cryopreserved intact human articular cartilage which can then be successfully cultured

During remodelling, osteoclasts produce discrete bone cavities filled with bone and this is associated with the dimensions of the cavity. The aim of this study is to investigate the effect of pores of similar size to those produced by osteoclasts on the morphology, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. The hypothesis is that a porous surface similar in morphology to a bone surface prepared by osteoclasts will increase cell proliferation and osteogenic differentiation of MSCs. Sheep BMSCs were seeded onto plain titanium surfaces and 100µm, 250µm and 500µm discrete pores surfaces. Cell metabolic activity was investigated using Presto Blue on days 3, 7 and 10. Bone mineralisation was quantified by Alizarin red staining at days 3, 7 and 14. Cell morphology was observed by scanning electron microscopy (SEM). Data was statistically analysed using one-way analysis of variance and a Bonferroni correction method. Cells on porous discs had a three dimensional phenotype and aligned on the circumference of each pore. Metabolic activity was significantly higher by day 10 on plain discs compared to all porous discs. Bone mineralization was significantly higher on 100µm pores by day 3 (0.545mM±0.66; p=0.047) than plain discs and significantly higher on both 100µm and 250µm pores by day 7(p=0.000 and p=0.005) than plain discs. Substantial mineralised bone matrix was found on 100µm discs without being treated with osteogenic supplements, compared to other control disc types (p=0.043, p=0.003, p=0.000). The different topographies altered cell behaviour and migration.100µm pores demonstrated earlier and enhanced bone mineralisation even in the absence of osteogenic supplements. This pore size is aligned to the size of individual resorption bays that osteoclasts produce on bone surfaces and is considerably lower than the pore sizes used to enhance osteo-integration of implant surfaces

Mesenchymal stem cells (MSCs) are believed to be immune-privileged due to lack of antigen-presenting-cell related markers, however, evidence suggests that MSCs are immunogenic and are attacked by the immune system. Our research investigates the hypothesis that there are differences between MSC clones from the same individual in terms of their morphology, proliferation, differentiation and immune profile. Our goal is to discover immune-privileged stem cells, which can act as a universal allogenic mesenchymal stem cell donor to facilitate bone ingrowth for osteosarcoma patients status post tumor excision and prosthesis implantation. Serial dilutions of bone-marrow derived (BMMSCs) and adipose derived mesenchymal stem cells (ADMSCs) from same animal were carried out in order to isolate single-cell clones. From a single animal we obtained 3 clones from BMMSCs and 3 from ADMSCs. This procedure was repeated for another other 2 animals. The proliferation rate and cell doubling time of each clonal culture was measured. The proliferation rate of mixed clonal cultures was also measured. The tri-differentiation potential of the clonal cultures was compared and a comparison was also made with the original isolates from bone marrow and fat. The immune-privileged properties were measured by flow cytometry and immuno-staining for the major histocompatibility complex (MHC) antigens. To measure the immune response a mixed leucocyte reaction was used but where leucocytes from a different individual were mixed with the clonal MSC cells. All isolates were able to differentiate into osteoblasts, chondrocytes and adipocytes. All clonal cultures revealed significantly different proliferation rates and doubling times when compared with each other and with mixed cultures. All clonal cultures showed different surface marker presentations, which included differences in the expression of MHC antigens. One clone isolated from ADMSCs showed lack of MHCI and MHCII. Our mixed leucocyte reaction and MHC staining showed variety of immune-modulation and this was related to the expression of the MHC antigens. All clones tri-differentiated and therefore show a degree of ‘stemness’. MSCs are generally are believed not to express MHC II and to be immune-privileged. However, this study shows that the expression of these antigens in clones isolated from bone marrow and from fat is variable. A heterogeneous result indicates individual differences between MSCs, even from same origin. The immune response elicited by MSCs is complicated. MSCs have been shown to release interleukin 10, which could inhibit the immune response but on the other hand interferon-gamma could enhance MHCII presentation in some MSCs. Our results confirmed our hypothesis because clonal cultures isolated from different sources of MSCs in the same animal showed significant differences in proliferation rate, morphology and surface marker presentation. Mesenchymal stem cells are not immunogenic or immune-privileged. Individual differences highlighted through single-cell clonal cultures may be the key to finding a universal immune-privileged MSCs for allogeneic transplantation

Mesenchymal stem cells (MSCs) are usually believed to be immune-privileged. However, immunogenic MSCs were also reported. We hypothesize that there are differences between MSC clones from the same individual in terms of their morphology, proliferation, differentiation and immunogenicity. Our goal is to discover immune-privileged stem cells for universal allogenic MSCs transplantation. Serial dilutions of bone-marrow derived (BMMSCs) and adipose derived mesenchymal stem cells (ADMSCs) from same animal were carried out to isolate single-cell clones. From a single animal we obtained 3 clones from BMMSCs and 3 from ADMSCs. The proliferation rate of each clonal culture and mixed clonal culture were measured. The tri-differentiation potential of the clonal cultures was compared, as well as with the original isolates from bone marrow and fat. The immune-privileged properties were measured by flow cytometry and immuno-staining for the major histocompatibility complex (MHC) antigens. Mixed leucocyte reaction (MLR) were also performed to investigate immunogenicity. Tri-differentiation was confirmed in all isolates. All clonal cultures revealed significant different morphology and proliferation rates, compared with each other and mixed cultures. All clonal cultures showed different surface markers, inclusive of MHC antigens. One clone from ADMSCs showed lack of MHC antigens. Our MLR and MHC staining disclosed variety of immune properties. All clones tri-differentiated which indicated a degree of ‘stemness’. MSCs are generally believed not to express MHC II, resulting in immune-privileged. Our results confirmed our hypothesis because clonal cultures isolated from different origins of same animal show differences in morphology, proliferation rate, and surface marker presentation. Individual immune differences highlighted through single-cell clonal cultures may be crucial to find universal immune-privileged MSCs as universal allogeneic donor

The growth plates of the femoral head of Japanese white rabbits aged 5, 10, 15 and 20 weeks were stained for apoptotic and proliferating chondrocytes using the TUNEL and PCNA antibody staining techniques. Both TUNEL- and PCNA-positive chondrocytes were detected in all of the specimens. The positive ratios of both stainings were calculated for the whole plate and for the resting, proliferating and hypertrophic zones. The highest ratios in both stainings occurred in the hypertrophic zone in all age groups. With growth, the TUNEL-positive ratio increased whereas the proliferating ratio decreased. We suggest that the increase in chondrocytic death by apoptosis and the decrease in cell proliferation potential led to closure of the growth plate

Bioreactors used in tissue engineering are mostly batch-fed with media added and removed periodically. Continuous flow bioreactors help increase ECM accumulation and cell proliferation, due to continuous flow of fresh media, thus, maintaining a steady extracellular nutrient environment. In previous work, we found chondrocytes cultured in continuous flow bioreactors with 20mM HEPES, accumulated considerably more matrix than static cultures. Hence, the objective of this study is to determine if NaHCO3 helps maintain a more physiological extracellular pH in the bioreactor, thus, enhancing ECM accumulation. Cartilaginous tissue constructs were generated from isolated chondrocytes harvested from the metacarpal joints of 12-18 month old calves. Cells were seeded in high-density 3D cultures (2 million cells/construct). Constructs were cultivated in a continuous flow bioreactor, with and without 14 mM NaHCO3 supplemented media, for 5 weeks, at 37 degrees Celsius, 95% relative humidity and 5% CO2. After 5 weeks of culture the tissue weight, thickness, pH and ECM deposition were determined. From the results obtained (Table 1), it is evident that chondrocytes cultured in the continuous flow bioreactor with 14mM NaHCO3 and 20mM HEPES, proliferated more extensively and produced more ECM than chondrocytes cultured in only 20mM HEPES. Additionally, the NaHCO3 constructs accumulated ECM in both the vertical (thickness) and horizontal (outgrowth) planes. The question then arises, are the effects mediated by improved buffering, or by addition of NaHCO3 itself. There was a significant difference between the pH of media with (pH 7.41) and without NaHCO3 (pH 6.95) supplementation, with no exposure to cells or tissue; when allowed to equilibrate with 5% CO2 at 37 degrees Celsius. However, there was little difference between the media after exposure to cells; after five weeks of culture in the bioreactor (Table 1). Thus, in the bioreactor with bicarbonate present, because of increased cell number and activity, the pH fell 0.54 pH units during the 7 hour residence time in comparison to the bioreactor with no bicarbonate supplementation. With no NaHCO3 supplementation, the extracellular pH of the medium fed to the cells was never above pH 7.0 (Table 1); low pH could account, at least in part, for lower ECM and cell numbers

Bovine and human articular chondrocytes were seeded in 2% alginate constructs and cultured for up to 19 days in a rotating-wall-vessel (RWV) and under static conditions. Culture within the RWV enhanced DNA levels for bovine chondrocyte-seeded constructs when compared with static conditions but did not produce enhancement for human cells. There was a significant enhancement of glycosaminoglycans and hydroxyproline synthesis for both bovine and human chondrocytes. In all cases, histological analysis revealed enhanced Safranin-O staining in the peripheral regions of the constructs compared with the central region. There was an overall increase in staining intensity after culture within the RWV compared with static conditions. Type-II collagen was produced by both bovine and human chondrocytes in the peripheral and central regions of the constructs and the staining intensity was enhanced by culture within the RWV. A capsule of flattened cells containing type-I collagen developed around the constructs maintained under static conditions when seeded with either bovine or human chondrocytes, but not when cultured within the RWV bioreactor.

Periprosthetic joint infections (PJI) are one of the most common reasons for orthopedic revision surgeries. In previous studies, it has been shown that silver modification of titanium (Ti-6Al-4V) surfaces by PMEDM (powder mixed electrical discharge machining) has an antibacterial effect on Staphylococcus aureus adhesion. Whether this method also influences the proliferation of bacteria has not been investigated so far. Furthermore, the effect is only limitedly investigated on the ossification processes. Therefore, the aim of this work is to investigate the antibacterial effect as well as the in vitro ossification process of PMEDM machined surfaces modified by integration of silver. In this study, we analyzed adhesion and proliferation of S. aureus in comparison to of surface roughness, silver content and layer thickness of the silver-integrated-PMEDM surfaces (N = 5). To test the in vitro ossification, human osteoblasts (SaOs-2) and osteoclasts (differentiated from murine-bone-marrow-macrophages) were cultured on the silver surfaces (N = 3). We showed that the attachment of S. aureus on the surfaces was significantly lower than on the comparative control surfaces of pure Ti-6Al-4V without incorporated silver, independently of the measured surface properties. Bacterial proliferation, however, was not affected by the silver content. No influence on the in vitro ossification was observed, whereas osteoclast formation was drastically reduced on the silver-modified surfaces. We showed that 1 to 3% of silver in the surface layer significantly reduced the adhesion of S. aureus, but not the proliferation of already attached bacteria. At the same time, no influence on the in vitro ossification was observed, while no osteoclasts were formed on the surface. Therefore, we state that PMEDM with simultaneous silver modification of the machined surfaces represents a promising technology for endoprostheses manufacturing to reduce infections while at the same time optimizing bone ingrowth

While high-performance ceramics like alumina and zirconia exhibit excellent wear resistance, they provide poor osseointegration capacity. As osseointegration is crucial for non-cemented joint prostheses, new techniques have been successfully developed for biofunctionalizing high-performance ceramic surfaces. Stable cell adhesion can be achieved by covalently bound specific peptides. In this study we investigate the effect of sterilization processes on organo-chemically functionalized surfaces. To enhance the performance of alumina-toughened zirconia ceramics (ATZ), a 3-aminopropyldiisopropylethoxysilane (APDS) monolayer was applied and coupled with cyclo-RGD peptides (cRGD) by using bifunctional crosslinker bis(sulfosuccinimidyl)suberat (BS³). The samples were sterilized using e-beam or gamma-sterilization at 25 kGy, either before or after biofunctionalization with cRGD. Functionalization stability was investigated by contact angle measurements. The functionality of cRGD after sterilization was demonstrated using proliferation tests and cytotoxicity assays. Immunofluorescence staining (pFAK, Actin, DAPI) was conducted to evaluate the adhesion potential between the samples and human mesenchymal stem cells (hMSCs). Functionalized samples before and after sterilization showed no significant difference regarding their contact angles. A proliferation test demonstrated that the cells on functionalized samples proliferate significantly more than on untreated samples before and after sterilization. hMSCs showed a significant higher proliferation on gamma sterilized samples compared to all other groups after 14 days. It was confirmed that the samples did not exhibit cytotoxic behavior before or after sterilization. Fluorescence microscopy demonstrated that both, cells on sterilized and on non-sterilized samples, expressed high levels of pFAK-Y397. The investigated functionalization enables improved adhesion and proliferation of hMSCs and is stable against the investigated sterilization processes. This is of importance as the option of having a sterile product enables the start of the translation of this biofunctional coating towards preclinical and subsequently first-in-man applications. Acknowledgments: We acknowledge the financial support of the Federal Ministry of Education and Research, BMBF (13GW0452A-C)

This study aimed to investigate the effect of irisin on human nucleus pulposus cells (hNPCs) in vitro. Our hypothesis was that irisin would improve hNPC metabolism and proliferation. hNPCs were isolated from intervertebral discs and cultured in alginate beads. hNPCs were exposed to phosphate-buffered saline (PBS) or recombinant irisin (r-irisin) at 5, 10 and 25 ng/mL (n=4). Each experiment was performed in triplicate. Cell proliferation was assessed with trypan blue staining-automated cell counting and PicoGreen assay. Glycosaminoglycan (GAG) content was measured using the DMMB assay. Metabolic activity was assessed with the MTT assay and the Griess Reagent System. Gene expression of collagen type II (COL2), matrix metalloproteinase (MMP)-13, tissue inhibitor of matrix metalloproteinase (TIMP)-1 and −3, aggrecan, interleukin (IL)-1β, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5 was measured by RT-PCR. MTT assay and ADAMTS-5, COL2, TIMP-1 and IL-1β gene expression were evaluated following incubation with 5, 10 and 25 ng/mL r-irisin for 24 hours and subsequent culture with 10 ng/ml IL-1β and vice versa (incubation for 24 hours with IL-1β and subsequent culture with r-irisin). Irisin increased hNPC proliferation (p<0.001), metabolic activity (p<0.05), GAG content (p<0.01), as well as COL2 (p<0.01), aggrecan (p<0.05), TIMP-1 and −3 (p<0.01) gene expression, while decreasing MMP-13 (p<0.05) and IL-1β (p<0.001) mRNA levels. r-irisin pretreatment of hNPCs cultured in pro-inflammatory conditions resulted in a rescue of metabolic activity (p<0.001) and a decrease of IL-1β (p<0.05) levels. Similarly, incubation of hNPCs with IL-1β and subsequent exposure to r-irisin increased hNPC metabolic activity (p<0.001), COL2 gene expression (p<0.05) and decreased IL-1β (p<0.05) and ADAMTS-5 levels (p<0.01). Irisin stimulates hNPC proliferation, metabolic activity, and anabolism by reducing IL-1β and catabolic enzyme expression while promoting matrix synthesis

Jellyfish collagens exhibit auspicious perspectives for tissue engineering applications primarily due to their outstanding compatibility with a wide range of cell types, low immunogenicity and biodegradability. Furthermore, derived from a non-mammalian source, jellyfish collagens reduce the risk of disease transmission, minimising therefore the ethical and safety concerns. The current study aims to investigate the potential of 3-dimensional jellyfish collagen sponges (3D-JCS) in promoting bone tissue regeneration. Both qualitative and quantitative analyses were performed in order to assess adhesion and proliferation of MC3T3 cells on 3D-JCL, as well as cell migration and bone-like ECM production. Histological and fluorescent dyes were used to stain mineral deposits (i.e. Alizarin Red S (ARS), Von Kossa, Tetracycline hydrochloride) while images were acquired using optical and confocal microscopy. Qualitative data indicated successful adhesion and proliferation of MC3T3 cells on the 3D-JCS as well as cell migration along with ECM production both on the inner and outer surface of the scaffolds. Moreover, quantitative analyses indicated a four-fold increase of ARS uptake between 2- and 3-dimensional cultures (N=3) as well as an eighteen-fold increase of ARS uptake for the 3D-JCS (N=3) when cultured in osteogenic conditions compared to control. This suggests the augmented osteogenic potential of MC3T3 cells when cultured on 3D-JCS. Nevertheless, the cell-mediated mineral deposition appeared to alter the mechanical properties of the jellyfish collagen sponges that were previously reported to exhibit low mechanical properties (compressive modulus: 1-2 kPa before culture). The biocompatibility, high porosity and pore interconnectivity of jellyfish collagen sponges promoted adhesion and proliferation of MC3T3 cells as well as cell migration and bone-like ECM production. Their unique features recommend the jellyfish collagen sponges as superior biomaterial scaffolds for bone tissue regeneration. Further studies are required to quantify the change in mechanical properties of the cell-seeded scaffolds and confirm their suitability for bone tissue regeneration. We predict that the 3D-JCS will be useful for future studies in both bone and bone-tendon interface regeneration. Acknowledgments. This research has been supported by a Medical Research Scotland Studentship award (ref: -50177-2019) in collaboration with Jellagen Ltd

Introduction:. Exercise has showed to reduce pain and improve function in patients with discogenic low back pain (LBP). Although there is currently no biologic evidence that the intervertebral disc (IVD) can respond to physical exercise in humans, a recent study has shown that chronic running exercise is associated with increased IVD hydration and hypertrophy1. Irisin, a myokine released upon muscle contraction, has demonstrated to yield anabolic effects on different cell types, including chondrocytes2. This study aimed to investigate the effect of irisin on human nucleus pulposus cells (hNPCs). Our hypothesis is that irisin may improve hNPCs metabolism and proliferation. METHODS:. The hNPCs, isolated from discectomy surgical waste material (n = 5), were expanded and encapsulated in alginate beads. The hNPCs were treated with: i) only growth medium (control); ii) medium with recombinant irisin (r-IR) at different concentrations (5, 10 and 25 ng / mL); iii) medium with Interleukin-1β (IL1β); iv) medium with IL1β for 24 h and then with IL1β and r-IR; v) medium with r-IR for 24 h and then with r-IR and IL1 β. We evaluated proliferation (trypan blue and PicoGreen), metabolic activity (MTT), nitrite concentration (Griess), and expression levels of catabolic and anabolic genes via real-time polymerase chain reaction (qPCR). Each analysis was performed in triplicate for each donor and each experiment was performed three times. Data were expressed as mean ± S.D. One-way ANOVA was used for the groups under exam. RESULTS:. Irisin increased hNPCs proliferation (p < 0.001), metabolic activity at 10 ng/mL (p < 0.05), and GAG content at concentration of 10 ng/mL and 25 ng/mL (p < 0.01; p < 0.001, respectively). The production of nitrites, used as an indicator of cellular oxidative stress, was significantly decreased (p < 0.01). Gene expression levels compared to the control group increased for COL2A1 (p < 0.01), ACAN (p < 0.05), TIMP-1 and −3 (p < 0.01), while a decrease in mRNA levels of MMP-13 (p < 0.05) and IL1β (p < 0.001) was noticed. r-IR pretreatment of hNPCs cultured in pro-inflammatory conditions resulted in a rescue of metabolic activity (p < 0.001), as well as a decrease of IL-1β (p < 0.05) levels. Similarly, incubation of hNPCs with IL-1β and subsequent exposure to r-IR led to an increment of hNPC metabolic activity (p < 0.001), COL2A1 gene expression (p < 0.05) and a reduction of IL-1β (p < 0.05) and ADAMTS-5 gene levels (p < 0.01). CONCLUSIONS:. The present study suggested that irisin may stimulate hNPCs proliferation, metabolic activity, and anabolism by reducing the expression of IL-1β and catabolic enzymes while promoting the synthesis of extracellular matrix components. Furthermore, this myokine was able to blunt the catabolic effect of in vitro inflammation. Our results indicate that irisin may be one of the mediators by which physical exercise and muscle tissues modulate IVD metabolism, thus suggesting the existence of a biological cross-talk mechanism between the muscle and the IVD

Articular cartilage is a relatively hypoxic tissue with a unique extracellular matrix that is enriched with cations, resulting in an elevated interstitial fluid osmolarity. Several biomechanical and physicochemical stimuli are reported to influence chondrocyte metabolism. For regenerative in vitro applications, increasing the extracellular osmolarity above plasma level to more physiological valuesinduces chondrogenic marker expression and the differentiation of chondroprogenitor cells. Calcineurin inhibitor FK506 modulates the differentiation of primary chondrocytes under such conditions and its effect on cell proliferation, extracellular matrix quality, and BMP- and TGF-β signaling will be described. Supraphysiological osmolarity compromises chondrocyte proliferation, while physosmolarity or FK506 did not. Rather, the combination of the latter increased proteoglycan and collagen expression in chondrocytesin vitro and in situ, affecting expression of TGF-β-inducible protein TGFBI and chondrogenic (SOX9, Col2) as well as terminal differentiation markers (e.g., Col10). Surprisingly, expression of particularly minor collagens (e.g., Col9, Col11) was improved. Physiological osmolarity seems to promote terminal chondrogenic differentiation of progenitor cells through sensitization of TGF-β superfamily signaling at the type I receptor. While hyperosmolarity alone facilitates TGF-β superfamily signaling, FK506 seems to enhance signaling by releasing the FKBP12 break from the type I receptor to improve collagenous marker expression. Our data help explaining seemingly contradictory earlier findings and potentially benefit future cell-based cartilage repair strategies

Total hip replacement (THR) is indicated for patients with osteoarthritis where conservative treatment has failed. Metal alloys used in THR implants such as cobalt-chromium (CoCr) have been known to cause pro-inflammatory reactions in patients, therefore leading to the need for costly revision surgery. This study therefore aimed to investigate the role of TLR4 in the activation of a human osteoblast model in response to CoCr particles in vitro. Human osteoblasts (MG-63 cell line) were seeded at a density of 100,000 cells and treated with 0.5, 5, 50mm3 CoCr particles per cell for 24-hours. Trypan blue and the XTT Cell Proliferation Kit II were then used in conjunction with the cells to assess CoCr-induced cytotoxicity. Cells were pre-treated with a commercially available TLR4-specific small molecule inhibitor (CLI-095) for 6 hours. Untreated cells were used as a negative control and lipopolysaccharide (LPS) was used as a positive control. Following treatment the cell supernatant was collected and used for enzyme-linked immunosorbant assay (ELISA) to measure the secretion of interleukin-8 (IL-8), CXCL10, and interleukin-6 (IL-6). Trypan blue and XTT analysis showed that there was no significant changes to cell viability or proliferation at any dose used of CoCr after 24 hours. There was a significant increase in protein secretion of IL-8 (p<0.001), CXCL10 (p<0.001), and IL-6 (p<0.001) in the cells which received the highest dosage of CoCr. This pro-inflammatory secretory response was ameliorated by TLR4 blockade (p<0.001). CoCr particles are not cytotoxic to osteoblasts but they do induce pro-inflammatory changes as characterised by increased secretion of chemokines IL-8, CXCL10, and IL-6. These responses occur via a TLR4-mediated pathway and upon inhibition they can be effectively ameliorated. This is particularly important as TLR4 could be a potential target for pharmacological intervention used in patients experiencing immunological reactions to metal implant debris

Degenerative disc disease, associated to low back pain, afflicts more than 50% of humans, and represents a major healthcare problem, especially for the pathology initiation. Current treatments range from conservative strategies to more invasive surgical techniques, such as disc removal and vertebral fusion. In the Intervertebral Disease (IVD) the nucleus pulposus (NP) degeneration is a key factor for the pathology initiation. Several tissue engineering approaches aiming to restore the appropriate NP cell (NPCs) and matrix content, were attempted by using adult stromal cells either from bone marrow or adipose tissue, chondrocytes, notochordal cells and more recently also pluripotent stem cells. However, none was fully satisfactory since the NP acid and a-vascularized environment appeared averse to the implanted heterologous cells. Several studies demonstrated the efficacy of platelet derivatives such as platelet rich plasma (PRP) in promoting the regeneration of connective tissues. We investigated the efficacy of PRP on NPCs proliferation and differentiation with the goal to propose the direct stimulation of resident cells (stimulation of endogenous cells – less invasive surgical procedure) or the implantation of NPCs expanded in vitro in the presence of PRP as therapeutic agents in IVD degeneration. NPCs were isolated from small fragments of NP explants, cultivated in medium supplemented with PRP or FCS (standard condition control) and characterized by FACS analysis for the expression of the typical mesenchymal stem cells markers CD34, CD44, CD45, CD73, CD90 and CD105. NPCs cultured in PL showed a phenotypic profile like the cells cultured in FCS. However, compared to NPCs expanded in the presence of FCS, NPCs expanded in PRP showed a much better proliferation and differentiation capacity. NPCs differentiation was evaluated by the cell ability to produce an organized metachromatic cartilaginous matrix, confirmed by the positive immunohistochemical staining for chondrogenic markers