The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity

Experimentally produced fractures in long bones studied by light and electron microscopic histochemistry were found to heal by a process of enchondral calcification. There was intense proliferation in the cells of the cambium layer of the periosteum, with differentiation to chondroblasts and osteoblasts, suggesting that this layer was the primary tissue responsible for development of the callus. Cytoplasmic processes of the hypertrophic chondrocytes appeared to bud and produce matrix vesicles. Alkaline phosphatase activity was detected along the plasma membrane of the hypertrophic chondrocytes and around the matrix vesicles, before any signs of mineral deposition. Calcification took place by deposition of hydroxyapatite crystals in and around these matrix vesicles which frequently showed alkaline phosphatase activity. It is suggested that there is a close functional association between alkaline phosphatase activity and calcification in the process of fracture healing, which is another type of enchondral calcification mediated by matrix vesicles

The aim of this study was to examine whether the assessment BsALP as a biochemical parameter in the early posttraumatic phase may indicate the course of fracture healing. The methods used for monitoring the bone healing process have been based on the patient’s subjective evaluation and radiographic findings. The activity of bone-specific alkaline phosphatase was measured in the sera of 41 patients who had sustained fractures of long bones. All the patients had been treated surgically. The activity of BsALP was assessed every seven days over a four-week period. The same patients were subject to radiology follow-ups for several months. Our research showed that the increase of alkaline phosphatase correlated with an increase of BsALP levels. The volume of callus correlated with a decrease, no change or an increase in the level of ALP and BsALP in the same way. It can be concluded that the monitoring of changes in the biochemical parameters of alkaline phosphatase and bone-specific alkaline phosphatase allows the early detection of the fracture healing dynamics

Osteomalacia may be a contributory factor in some patients in the development of fractures of the femoral neck and complicate the subsequent management. The level of serum alkaline phosphatase is often valuable in the diagnosis of metabolic bone disease but rises after any uncomplicated fracture, and since such a rise may limit the diagnostic usefulness of this measurement in detecting osteomalacia its extent was assessed in 106 patients. In the majority serum levels were normal on admission, rising after seven to nine days to reach a maximum within a month after fracture. Elevated levels on admission were found in patients with osteomalacia, liver damage or where there had been a delay of several weeks between injury and admission. In a small number of patients normal levels on admission subsequently reached very high values, usually in association with comminution or instability of the fracture. Elevated levels persisted for six to twelve weeks after fracture, the major influence upon the level at this time being the maximum value achieved rather than the presence of osteomalacia. If patients are to be screened for osteomalacia, the alkaline phosphatase must be measured within the first week after a fracture to avoid the distorting influences of the fracture itself

Estimations of serum alkaline phosphatase were carried out prospectively on a series of patients having a total hip replacement. The levels of serum alkaline phosphatase before operation indicated a group of patients who subsequently developed heterotopic ossification. Levels of this enzyme after operation did not indicate those patients who were developing heterotopic ossification

The acid and alkaline phosphatase activity in fluid aspirated from solitary bone cysts in six patients was measured, and large increases in the concentration of acid phosphatase were found. In some cases this increase was reflected in venous blood concentrations. The significance of these findings for the pathogenesis and the management of solitary bone cyst is discussed

Aims: The aim of the research is the functionalization of biosurfaces by anchoring on them biomolecules involved in the process of osteointegration (cellular adhesion, proliferation, differentiation, migration, matrix mineralization). Alkaline phosphatase (ALP) was used as model protein, because it is involved in the mineralization processes. The functionalized surfaces are biomimetic, because they show the biological signals triggering new tissue generation. A rapid osseointegration are the final goal and a good response and fast healing of bad quality bones is one of the main issues. The devices of interest for the research are dental or orthopaedic implants and substitutes of small bones. Methods: Bioactive glasses of various compositions were employed as substrates. Bioactive glasses, when in contact with biological fluids, stimulate the precipitation of a hydroxyapatite layer on their surfaces, which in turn promotes effective osteointegration of the implant. Since bioactive glasses are prone to hydroxylation, they could be successfully functionalized and grafted by biomolecules. So the biomimetic materials considered will be bioactive both from a physicochemical (osteoconduction and apatite precipitation) and from a biochemical (osteoinduction) point of view. The research was focused first of all on the methods for developing active sites on the substrates. In the case of bioactive glasses the surface must be cleaned of any contaminants and the reactive hydroxyls activated. Results: The immobilization of ALP was performed both with and without spacer molecules and a comparison among the different techniques will be presented. XPS was used for the analysis of the immobilized enzyme on titanium and bioglasses and specific signals for its identification were set. After the addition of the specific substrate, the ALP activity was evaluated by UV-VIS spectroscopy. Conclusions: ALP was successfully grafted on the surface of bioactive glasses with and without the use of an intermediate layer of spacer molecules. The presence of ALP was determined on all the samples, as well as its enzymatic activity. Further analyses are necessary to evaluate the opportunity of using a spacer molecule. Cell adhesion and proliferation tests are in progress

Mesenchymal stromal cells (MSCs) have been intensively researched in the orthopaedic field since they hold great promise for aiding the regeneration of musculoskeletal tissues. While there are a range of postulated surface markers to identify MSCs, currently there are no known cell markers that predict in vivo osteochondral potency. Runt-related transcription factor 2 (Runx2) is considered as an essential transcription factor in osteoblast differentiation [1] and has been shown to physically interact with retinoblastoma protein (pRb), which leads the loss of osteoblast proliferation and the activation of genes concerning terminal differentiation of osteoblasts [2]. The aim of this study was to use adenoviral-mediated gene overexpression/knockdown to investigate the interplay between Runx2 and pRb during in vitro osteogenic differentiation of human bone marrow (hBM)-MSCs. A first generation human adenovirus (hAd) serotype 5 dE/E3 carrying the gene of interest (Runx2 or shRNA-Runx2) were propagated and amplified in AD-293 cells, and purified over successive CsCl gradients. A second generation hAd serotype 5 carrying the gene of interest (Rb1) was generated. High efficiency single or double transduction of undifferentiated hBM-MSCs was achieved using lanthofection [3]. The transduced hBM-MSCs were then differentiated in osteogenic medium (OM) and osteogenic potency was assessed by quantification of alkaline phosphatase (ALP) activity (day 14) and Alizarin red staining (day 28). In addition, cell cultures were assessed for absorbance at OD 450nm, correlating to the refractive index of calcified areas, at days 0, 7, 14, 21 and 28 [4]. Quantitative RT-PCR was used to confirm expression of target genes following viral transduction. Basal medium was used as a control. Untransduced hBM-MSCs cultures grown in OM demonstrated peak calcium deposition at day 28, while the overexpression of either Runx2 or Rb1 accelerated peak calcium deposition to day 21. Consistent with this, Runx2 overexpression increased ALP activity of hBM-MSCs cultured in OM, while Rb1 overexpression enhanced ALP activity of hBM-MSCs cultured in both basal and osteogenic conditions. Co-expression of Runx2 and Rb1 did not further increase ALP activity compared to cells transduced with Runx2 or Rb1 alone. Alizarin red staining revealed that overexpression of either Runx2 or Rb1 increased mineral deposition in hBM-MSCs under basal conditions, although mineralisation was not enhanced above that of untransduced cells when cultured in OM. However, mineralisation was markedly enhanced above levels in untransduced cells when Runx2 and Rb1 were co-expressed in hBM-MSCs grown under both basal and osteogenic conditions. This study demonstrates an important stimulatory role of pRb in enhancing ALP activity of hBM-MSCs in the absence of osteogenic clues. However, pRb overexpression alone is insufficient to enhance mineralisation, requiring the co-expression of Runx2 in hBM-MSCs. The crucial nature of Runx2 for osteogenic differentiation of hBM-MSCs was demonstrated since knockdown of Runx2 prevented both mineral deposition and the increased ALP activity observed in untransduced cells grown in OM. Interestingly, overexpression of Rb1 could not compensate for the knockdown of Runx2 since Rb1 overexpression did not recover either mineral deposition or ALP activity in hBM-MSCs where Runx2 expression was inhibited

Mesenchymal stem cells (MSC) are suitable candidates for the cell-based cartilage reconstruction and have been isolated from different sources such as bone marrow (BMSC), adipose tissue (ATSC) and synovium (SMSC). The aim of this study was to analyse the tendency of BMSC, ATSC and SMSC to undergo hypertrophy during chondrogenic induction in vitro and to evaluate their in vivo development after ectopic transplantation into SCID mice in order to determine which cell source is most suitable for cartilage regeneration. Human BMSC, ATSC and SMSC were cultured under chondrogenic conditions for five weeks. Differentiation was evaluated based on histology, gene expression, and analysis of alkaline phosphatase activity (ALP). Pellets were transplanted subcutaneously into SCID mice after chondrogenic induction for 5 weeks and analysed 4 weeks later by histology. Similar COL2A1:COL10A1 mRNA ratios were found in BMSC, ATSC and SMSC. BMSC displayed the highest ALP activities, SMSC had lower and heterogenic ALP activities in vitro which correlated with calcification of spheroids in vivo. Most SMSC transplants specifically lost their collagen type II in vivo or were fully degraded. BMSC and ATSC pellets always underwent vascular invasion and calcification in vivo. Single BMSC samples had the capacity to develop into woven bone or fully developed ossicles with hematopoietic tissue surrounded by a bone capsule. Neither BMSC nor ATSC or SMSC were able to form stable ectopic cartilage. While BMSC and ATSC underwent developmental processes related to endochondral ossification instead of stable ectopic cartilage formation, SMSC tended to undergo fibrous dedifferentiation or degradation. Besides appropriate induction of chondrogenesis, locking of cells in the desired differentiation state is, thus, a further challenge for adult stem cell-based cartilage repair

Objective: The clinical significance of biochemical bone markers in the diagnosis and severity of Osteoarthritis remains still unknown. The relationship between biochemical bone turnover markers and commonly recognizable radiographic features of knee and hip osteoarthritis remains unclear. Purpose: We evaluated the serum levels of Receptor Activator of Nuclear Factor-κB Ligand (RANKL), Bone-specific Alkaline Phosphatase (b-ALP), Osteocalcin and Osteoprotegerin in two groups of patients suffering from osteoarthritis of the Knee or Hip respectively, aiming to correlate these results with the radiographically assessed severity of the disease and the patients’ age. The results between the two groups were also compared. Patients-Methods: Between March 2007 and February 2009, a total of 175 patients suffering from Knee or Hip Osteoarthritis were enrolled in the study. Following proper radiographic evaluation, the osteoarthritic changes of patients were graded by 3 orthopaedic surgeons according to the system of Kellgren and Lawrence; at the same time the serum levels of biochemical markers were determined. Results: Osteoprotegerin was found to be positively correlated with age in both the Knee (r=0.376, p=0.000) and Hip (r=0.425, p=0.001) group, whether Osteocalcin was significantly correlated with the age in the group of Knee Osteoarthritis(r=0.218, p=0.02). No other significant correlation was noted between the serum level of markers and age of patients in both groups. There was not significant difference in the mean serum level of biochemical markers among patients belonging to each of the four different levels of severity of hip and knee OA. There was no significant impact of the type of Osteoarthritis, to the serum level of all biochemical markers. Conclusions: Based on our results, it seems that none of the serum biochemical markers studied can be used (either independently or in combination with the others) as surrogates for radiographic imaging in Hip and Knee osteoarthritis

Aims. Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 μg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells. Methods. Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies. Results. The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 μg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 μg/ml, and ALP activity was significantly decreased at ≥ 750 μg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 μg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 μg/ml on day 21 and at 500 μg/ml on day 28, and ALP activity was significantly decreased at 500 μg/ml on day 28. Conclusion. Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting. Cite this article: Bone Joint Res 2024;13(3):91–100

Aims. This study aimed to demonstrate the promoting effect of elastic fixation on fracture, and further explore its mechanism at the gene and protein expression levels. Methods. A closed tibial fracture model was established using 12 male Japanese white rabbits, and divided into elastic and stiff fixation groups based on different fixation methods. Two weeks after the operation, a radiograph and pathological examination of callus tissue were used to evaluate fracture healing. Then, the differentially expressed proteins (DEPs) were examined in the callus using proteomics. Finally, in vitro cell experiments were conducted to investigate hub proteins involved in this process. Results. Mean callus volume was larger in the elastic fixation group (1,755 mm. 3. (standard error of the mean (SEM) 297)) than in the stiff fixation group (258 mm. 3. (SEM 65)). Pathological observation found that the expression levels of osterix (OSX), collagen, type I, alpha 1 (COL1α1), and alkaline phosphatase (ALP) in the callus of the elastic fixation group were higher than those of the stiff fixation group. The protein sequence of the callus revealed 199 DEPs, 124 of which were highly expressed in the elastic fixation group. In the in vitro study, it was observed that a stress of 200 g led to upregulation of thrombospondin 1 (THBS1) and osteoglycin (OGN) expression in bone marrow mesenchymal stem cells (BMSCs). Additionally, these genes were found to be upregulated during the osteogenic differentiation process of the BMSCs. Conclusion. Elastic fixation can promote fracture healing and osteoblast differentiation in callus, and the ability of elastic fixation to promote osteogenic differentiation of BMSCs may be achieved by upregulating genes such as THBS1 and OGN. Cite this article: Bone Joint Res 2024;13(10):559–572

Background: The clinical significance of bone turnover markers is well recognized, at least in several diseases affecting the bone metabolism. However, their clinical significance (if any) remains still unknown in patients undergoing Total Joint Arthroplasty (TJA). Changes in the levels of some markers have been reported in the early postoperative period after Total Hip Arthroplasty; however their exact postoperative course has not been clearly documented yet. In order to assess the clinical value of biochemical markers when trying to determine the fixation of orthopaedic implants, it is necessary to clarify their normal postoperative course.

The aim of this study was to extend the evaluation of the course of bone turnover markers over a longer period (12 postoperative months) following a TJA, and to assess the postoperative course for two of them (RANKL and Osteoprotegerin) for the first time.

Methods: The serum levels of RANKL, Osteocalcin, Osteoprotegerin and bALP were determined one day preoperatively and several times during the first postoperative year in patients suffering from idiopathic osteoarthritis that underwent total knee (n=23) and hip arthroplasties (n=24).

Results: There were statistically significant changes in the serum levels of all markers over time (p< 0,001). RANKL values initially increased and then gradually decreased. Following an initial decrease, Osteocalcin values continuously increased until the 2nd postoperative month and then continuously decreased. Osteoprotegerin initially increased, then decreased until the 4th postoperative month and then increased again reaching a peak 8 months postoperatively. Bone-specific ALP decreased until the 7th postoperative day. After that time it continuously increased, reaching a peak at the 8th month, and then it gradually decreased. There were no major differences in the postoperative course of all markers between the hip and knee arthroplasties.

Conclusions: The levels of all bone markers did not uniformly ‘return’ to their preoperative values one year postoperatively. A one-year period is not enough, when assessing an orthopaedic implant’s fixation with the use of bone turnover markers.

Aims. The aim of this study was to report the long-term prognosis of patients with multiple Langerhans cell histiocytosis (LCH) involving the spine, and to analyze the risk factors for progression-free survival (PFS). Methods. We included 28 patients with multiple LCH involving the spine treated between January 2009 and August 2021. Kaplan-Meier methods were applied to estimate overall survival (OS) and PFS. Univariate Cox regression analysis was used to identify variables associated with PFS. Results. Patients with multiple LCH involving the spine accounted for 15.4% (28/182 cases) of all cases of spinal LCH: their lesions primarily involved the thoracic and lumbar spines. The most common symptom was pain, followed by neurological dysfunction. All patients presented with osteolytic bone destruction, and 23 cases were accompanied by a paravertebral soft-tissue mass. The incidence of vertebra plana was low, whereas the oversleeve-like sign was a more common finding. The alkaline phosphatase was significantly higher in patients with single-system multifocal bone LCH than in patients with multisystem LCH. At final follow-up, one patient had been lost to follow-up, two patients had died, three patients had local recurrence, six patients had distant involvement, and 17 patients were alive with disease. The median PFS and OS were 50.5 months (interquartile range (IQR) 23.5 to 63.1) and 60.5 months (IQR 38.0 to 73.3), respectively. Stage (hazard ratio (HR) 4.324; p < 0.001) and chemotherapy (HR 0.203; p < 0.001) were prognostic factors for PFS. Conclusion. Pain is primarily due to segmental instability of the spine from its destruction by LCH. Chemotherapy can significantly improve PFS, and radiotherapy has achieved good results in local control. The LCH lesions in some patients will continue to progress. It may initially appear as an isolated or single-system LCH, but will gradually involve multiple sites or systems. Therefore, long-term follow-up and timely intervention are important for patients with spinal LCH. Cite this article: Bone Joint J 2023;105-B(6):679–687

Aims. To investigate whether idiopathic osteonecrosis of the femoral head (ONFH) is related to impaired osteoblast activities. Methods. We cultured osteoblasts isolated from trabecular bone explants taken from the femoral head and the intertrochanteric region of patients with idiopathic ONFH, or from the intertrochanteric region of patients with osteoarthritis (OA), and compared their viability, mineralization capacity, and secretion of paracrine factors. Results. Osteoblasts from the intertrochanteric region of patients with ONFH showed lower alkaline phosphatase (ALP) activity and mineralization capacity than osteoblasts from the same skeletal site in age-matched patients with OA, as well as lower messenger RNA (mRNA) levels of genes encoding osteocalcin and bone sialoprotein and higher osteopontin expression. In addition, osteoblasts from patients with ONFH secreted lower osteoprotegerin (OPG) levels than those from patients with OA, resulting in a higher receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) ligand (RANKL)-to-OPG ratio. In patients with ONFH, osteoblasts from the femoral head showed reduced viability and mineralized nodule formation compared with osteoblasts from the intertrochanteric region. Notably, the secretion of the pro-resorptive factors interleukin-6 and prostaglandin E. 2. as well as the RANKL-to-OPG ratio were markedly higher in osteoblast cultures from the femoral head than in those from the intertrochanteric region. Conclusion. Idiopathic ONFH is associated with a reduced mineralization capacity of osteoblasts and increased secretion of pro-resorptive factors. Cite this article: Bone Joint Res 2021;10(9):619–628

Aims. The association of auraptene (AUR), a 7-geranyloxycoumarin, on osteoporosis and its potential pathway was predicted by network pharmacology and confirmed in experimental osteoporotic mice. Methods. The network of AUR was constructed and a potential pathway predicted by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) terms enrichment. Female ovariectomized (OVX) Institute of Cancer Research mice were intraperitoneally injected with 0.01, 0.1, and 1 mM AUR for four weeks. The bone mineral density (BMD) level was measured by dual-energy X-ray absorptiometry. The bone microstructure was determined by histomorphological changes in the femora. In addition, biochemical analysis of the serum and assessment of the messenger RNA (mRNA) levels of osteoclastic markers were performed. Results. In total, 65.93% of the genes of the AUR network matched with osteoporosis-related genes. Osteoclast differentiation was predicted to be a potential pathway of AUR in osteoporosis. Based on the network pharmacology, the BMD and bone mineral content levels were significantly (p < 0.05) increased in the whole body, femur, tibia, and lumbar spine by AUR. AUR normalized the bone microstructure and the serum alkaline phosphatase (ALP), bone-specific alkaline phosphatase (bALP), osteocalcin, and calcium in comparison with the OVX group. In addition, AUR treatment reduced TRAP-positive osteoclasts and receptor activator of nuclear factor kappa-B ligand (RANKL). +. nuclear factor of activated T cells 1 (NFATc1). +. expression in the femoral body. Moreover, the expressions of initiators for osteoclastic resorption and bone matrix degradation were significantly (p < 0.05) regulated by AUR in the lumbar spine of the osteoporotic mice. Conclusion. AUR ameliorated bone loss by downregulating the RANKL/NFATc1 pathway, resulting in improvement of osteoporosis. In conclusion, AUR might be an ameliorative cure that alleviates bone loss in osteoporosis via inhibition of osteoclastic activity. Cite this article: Bone Joint Res 2022;11(5):304–316

Objectives

Effects of insulin-like growth factor 1 (IGF1), fibroblast growth factor 2 (FGF2) and bone morphogenetic protein 2 (BMP2) on the expression of genes involved in the proliferation and differentiation of osteoblasts in culture were analysed. The best sequence of growth factor addition that induces expansion of cells before their differentiation was sought.

Aims. Astragalus polysaccharide (APS) participates in various processes, such as the enhancement of immunity and inhibition of tumours. APS can affect osteoporosis (OP) by regulating the osteogenic differentiation of human bone mesenchymal stem cells (hBMSCs). This study was designed to elucidate the mechanism of APS in hBMSC proliferation and osteoblast differentiation. Methods. Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting were performed to determine the expression of microRNA (miR)-760 and ankyrin repeat and FYVE domain containing 1 (ANKFY1) in OP tissues and hBMSCs. Cell viability was measured using the Cell Counting Kit-8 assay. The expression of cyclin D1 and osteogenic marker genes (osteocalcin (OCN), alkaline phosphatase (ALP), and runt-related transcription factor 2 (RUNX2)) was evaluated using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Mineral deposits were detected through Alizarin Red S staining. In addition, Western blotting was performed to detect the ANKFY1 protein levels following the regulation of miR-760. The relationship between miR-760 and ANKFY1 was determined using a luciferase reporter assay. Results. The expression of miR-760 was upregulated in OP tissues, whereas ANKFY1 expression was downregulated. APS stimulated the differentiation and proliferation of hBMSCs by: increasing their viability; upregulating the expression levels of cyclin D1, ALP, OCN, and RUNX2; and inducing osteoblast mineralization. Moreover, APS downregulated the expression of miR-760. Overexpression of miR-760 was found to inhibit the promotive effect of APS on hBMSC differentiation and proliferation, while knockdown of miR-760 had the opposite effect. ANKFY1 was found to be the direct target of miR-760. Additionally, ANKFY1 participated in the APS-mediated regulation of miR-760 function in hBMSCs. Conclusion. APS promotes the osteogenic differentiation and proliferation of hBMSCs. Moreover, APS alleviates the effects of OP by downregulating miR-760 and upregulating ANKFY1 expression. Cite this article: Bone Joint Res 2023;12(8):476–485