Osteosarcoma is common in children and adolescents with high mortality due to rapid progression. Therapeutic approaches for osteosarcoma are limited and may cause side effects. Cannabinoid ligands exert antiproliferative, apoptotic effect in cancer cells via CB1/2 or TRPV1 receptors. In this study, we hypothesized that synthetic specific CB2R agonist CB65 might have an antiproliferative and apoptotic effect on osteosarcoma cell lines in vitro. If so, this agent might be a chemotherapeutic candidate for osteosarcoma, with prolonged release, increased stability and bioavailability when loaded into a liposomal system. We first determined CB2 receptor expression in MG63 and Saos-2 osteosarcoma cells by qRT- PCR and FCM. CB65 reduced proliferation in osteosarcoma cells by WST-1 and RTCA. IC50 for MG63 and Saos-2 cells were calculated as 1.11×10-11 and 4.95×10-11 M, respectively. The antiproliferative effect of CB65 on osteosarcoma cells was inhibited by CB2 antagonist AM630. IC50 of CB65 induced late apoptosis of MG63 and Saos-2 cells at 24 and 48 hours, respectively by FCM. CB65 was loaded into the liposomal system by thin film hydration method and particle size, polydispersity index, and zeta potentials were 141.7±0.6 nm, 0.451±0.026, and -10.9±0.3 mV, respectively. The CB65-loaded liposomal formulation reduced MG63 and Saos-2 cell proliferation by RTCA. IC50 of CB65 and CB65-loaded liposomal formulation induced late apoptosis of MG63 and Saos-2 cells at 24 and 48 hours, respectively, by FCM. Scratch width was higher in CB65 and CB65-loaded liposome-treated cells compared to control. In this study, the real-time antiproliferative and apoptotic effect of synthetic specific CB2 agonist CB65 in osteosarcoma cell lines was demonstrated for the first time, and the real time therapeutic window was determined. The CB65-loaded liposomal formulation presents a potential treatment option that can be translated to clinic following its validation within animal models and production under GMP conditions

Osteosarcoma is a highly malignant primary tumor of bone tissue. The 5-year survival rate of patients with metastasis is below 20% and this scenario is unchanged in the last two decades, despite great efforts in pre-clinical and clinical research. Traditional preclinical models of osteosarcoma do not consider the whole complexity of its microenvironment, leading to poor correlation between in vitro/in vivo results and clinical outcomes. Spheroids are a promising in vitro model to mimic osteosarcoma and perform drug-screening tests, as they (i) reproduce the microarchitecture of the tumor, (ii) are characterized by hypoxic regions and necrotic core as the in vivo tumor, (iii) and recapitulate the chemo-resistance phenomena. However, to date, the spheroid model is scarcely used in osteosarcoma research. Our aim is to develop a customized culture dish to grow and characterize spheroids and to perform advanced drug-screening tests. The resulting platform must be adapted to automated image acquisition systems, to overcome the drawbacks of commercial spheroids platforms. To this purpose, we designed and developed a micro-patterned culture dish by casting agarose on a 3D printed mold from a CAD design. We successfully obtained viable and reproducible homotypic osteosarcoma spheroids, with two different cells lines from osteosarcoma (i.e., 143b and MG-63). Using the platform, we performed viability assays and live fluorescent stainings (e.g., Calcein AM) with low reagent consumption. Moreover, the culture dish was validated as drug screening platform, administrating Doxorubicin at different doses, and evaluating its effect on OS spheroids, in terms of morphology and viability. This platform can be considered an attractive alternative to the highly expensive commercial spheroid platforms to obtain homogeneous and reproducible spheroids in a high-throughput and cost effective mode

Macrophages (Mφ) are immune cells that play a crucial role in both innate and adaptive immunity as they are involved in a wide range of physiological and pathological processes. Depending on the microenvironment and signals present, Mφ can polarize into either M1 or M2 phenotypes, with M1 macrophages exhibiting pro-inflammatory and cytotoxic effects, while M2 macrophages having immunosuppressive and tissue repair properties. Macrophages have been shown to play key roles in the development and progression or inhibition of various diseases, including cancer. For example, macrophages can stimulate tumor progression by promoting immunosuppression, angiogenesis, invasion, and metastasis. This work aimed to investigate the effect of extracellular vesicles (EVs)-derived from polarized macrophages on an osteosarcoma cell line. Monocytes were extracted from buffy coats and cultured in RPMI medium with platelet lysate or M-CSF. After 6 days of seeding, Mφ were differentiated into M1 and M2 with INF-γ/LPS and IL-4/IL-13, respectively. The medium with M1 or M2 derived EVs was collected and EVs were isolated by differential centrifugation and size exclusion chromatography and its morphology and size were characterized with SEM and NTA, respectively. The presence of typical EVs markers (CD9, CD63) was assessed by Western Blot. Finally, EVs from M1 or M2-polarized Mφ were added onto osteosarcoma cell cultures and their effect on cell viability and cell cycle, proliferation, and gene expression was assessed. The EVs showed the typical shape, size and surface markers of EVs. Overall, we observed that osteosarcoma cells responded differentially to EVs isolated from the M1 and M2-polarized Mφ. In summary, the use of Mφ-derived EVs for the treatment of osteosarcoma and other cancers deserves further study as it could benefit from interesting traits of EVs such as low immunogenicity, nontoxicity, and ability to pass through tissue barriers. Acknowledgements: Carlos III Health Institute and the European Social Fund for contract CP21/00136 and project PI22/01686

Summary Statement. In this study we suggested a possible role of prion proteins genes in osteosarcoma. Therefore, the inhibition of prion proteins expression must be tested because it could represent a new approach to the molecular treatment of osteosarcoma. Introduction. Although osteosarcoma is the most common bone malignancy, the molecular and cellular mechanisms influencing its pathogenesis have remained elusive. Prion proteins (PRNP and PRND), known mostly for its involvement in neurodegenerative spongiform encephalopathies, have been recently demonstrated to be involved in resistance to apoptosis, tumorigenesis, proliferation and metastasis. Patients & Methods. The main aim of research was to study whether prion proteins were over-expressed in human osteosarcoma, and if prion proteins could have a role also in osteosarcomas. We evaluated differential gene expression between 22 cases of osteosarcoma and 40 cases of normal bone specimens through cDNA microarray analysis spanning a substantial fraction of the human genome. Results. PRNP and PRND are significantly over-expressed in osteosarcoma. PRNP and PRND appear involved with some important genes related to tumorigenesis and apoptosis. PRNP is linked to PTK2, RBBP9 and TGFB1 while PRND is linked to TNFSF10, BCL2A1, NFKB2 and TP53RK. Discussion/Conclusion. Increased expression on Affymetrix arrays of prion proteins seems to be associated with the development of osteosarcoma. Prions seem to induce a negative regulation of apoptosis, thus promoting osteosarcoma development and progression. Osteosarcoma is a very aggressive tumor and even after modern chemotherapy and excision of tumors efforts are needed to improve clinical outcome. Since Prion proteins seem to be related to osteosarcoma development, their inhibition could represent a new approach to the molecular treatment of osteosarcoma

Summary Statement. Combination of sorafenib with irradiation achieved synergistic effect with dose reduction in both 143B and HOS cell lines. This demonstrated the potential application of sorafenib in the treatment of osteosarcoma metastasis and radiation resistance. Introduction. More than 20% of patients with osteosarcoma die of the disease within 5 years due to tumour relapse and metastasis. Identifying new treatment that works singly or in combination with conventional therapies is urgently required. We previously found that the Ras/Raf/MAPK pathway was associated with lung metastasis in a 143B inoculated osteosarcoma orthotopic mouse model. 1. Sorafenib, a multi-kinase inhibitor, has shown potent anticancer effect including in osteosarcoma. 2. through the inhibition of Raf-1 and other targets. 3. The aims of this study were to investigate effect of sorafenib on osteosarcoma cell lines with or without activated Ras/Raf/MAPK signalling and to decide whether sorafenib could enhance irradiation on these cells. Materials and Methods. Osteosarcoma cell lines 143B (HOS with Ras gene transfection), HOS and U2OS were used. Clonogenic assay was applied for assessing tumour growth and colony formation with or without treatment. Sorefenib was provided by Bayer gratis. Irradiation was performed using the Therapax DXT300 Orthovoltage Radiation System (Pantak, Connecticut, USA). Three doses of sorafenib (1, 2, 4 ug/ml) and three doses of radiation (50, 100, 200 cGy) were used with vehicle controls. In the combination therapy sorafenib was given at pre-, concurrent and post-irradiation. Each treatment was duplicated with the experiment being repeated once. Results. Sorafenib monotherapy achieved 50% inhibition (EC50) effects in all three tested cell lines with 7.05 ug/ml for 143B, 1.59 for HOS and 2.41 for U2OS. The 143B cell line was seriously resistant to irradiation with EC50 of 167 Gy, whilst other cell lines were relatively sensitive (HOS, 1.5 Gy and U2OS, 1.0 Gy). Combination of sorafenib with irradiation achieved synergistic effect with dose reduction in both 143B and HOS cell lines, but no obvious effect in U2OS cells. Discussion. Sorafenib demonstrated inhibitory effects on cell growth and colony formation even in a Ras/Raf/MAPK signalling activated osteosarcoma cell line, suggesting its potential application in the treatment of some metastatic osteosarcoma. Activated Ras/Raf/MAPK signalling is one of the mechanisms of radiation resistance and the synergistic effect of soratenib with irradiation combination therapy in this cell population indicated it's potential application in the treatment of irradiation resistant osteosarcoma. The dose reduction achieved by this combination could benefit patients with less specific side effects

Summary. Reciprocal metabolic reprogramming of MSCs and osteosarcoma cells influences tumor-stroma cross talk. Drugs targeting Warburg metabolism may define innovative therapeutic approaches in osteosarcoma. Introduction. Osteosarcoma (OS) is a malignant primary bone tumour of mesenchymal origin, in which cells with stem-like characteristics (CSCs) have been described. Recent studies have demonstrated a mutual interaction between stroma and tumor cells in exploiting a role in the pathogenesis and progression of cancer, and also in the enhancing stemness phenotype. Here we take in consideration the complex juxtacrine and paracrine intercellular cross talk played by mesenchymal stromal cells (MSCs) with adherent osteosarcoma cells and OS cells with stem-like characteristics (CSCs). Methods. MSCs were isolated from human adipose tissue and expanded. To evaluate the interaction between the stroma and the cancer cell compartment, we used two different osteosarcoma cancer cell lines (Saos-2 and HOS) and co-cultured them with MSCs. The different cell populations were sorted to study the reciprocal interaction including metabolic reprogramming. CSCs were obtained from SAOS-2 and HOS cell lines using the sphere formation assay and characterised for their self-renewal, mesenchymal stem cell properties and expression of pluripotency markers. CSCs sensitivity to paracrine factors produced by human MSCs was analysed in a model of co-culture system. Mitochondrial activity in the co-culture systems was also evaluated. Results. Our results revealed that upon intercellular contact, MSCs undergo Warburg metabolism and mitochondrial oxidative stress. In particular, the cell contact activated the stromal component, triggering autophagy and increased expression of monocarboxylate transporter-4 (MCT4) responsible for the extrusion of lactate. Conversely, osteosarcoma cancer cells, upon contact with MSCs, increased their aerobic metabolism and their development. In addition, using a co-culture method without cell contact, we observed that MSCs grown in serum-starvation conditions promoted proliferation of the CSCs obtained from OS cells, probably by secreting one or several soluble factors. By Real Time PCR we evaluated the gene expression of stemness markers like Oct4, Nanog and SOX2, which appeared to have increased in CSCs. Conclusions. The final goal is to have a better understanding of the role of the stroma on tumor cell metabolism. Apparently, our data show that MSCs may exploit a role in the modulation of tumor metabolic activity and stemness/differentiation in osteosarcoma. Importantly, these findings suggest an adaptation of cancer cells to bioenergetic changes “engaging” stromal cells as their survival strategy. Understanding the interactions in the tumor microenvironment should present new opportunities for the design of cancer therapeutics

Our goal is to repurpose drugs to block the growth of lung metastases, the lethal process in osteosarcoma. We therefore screened the NCI-panel of 114 FDA-approved oncology drugs to identify agents that potently reduce growth of osteosarcoma spheroids (sarcospheres). We first developed a system to routinely generate large numbers of highly-uniform spherical sarcospheres (1/well) with a 400um diameter, to most closely simulate micrometatases. Our primary drug screen (Z’-factor=0.70+0.10) utilized sarcospheres from three highly-metastatic human osteosarcoma cell lines (LM7, 143B, and MG63.3) in the presence and absence of MAP chemotherapeutics. Dose-response experiments with 13 of the most effective drugs confirmed initial results and allowed comparison with each drug's toxicity on normal human osteoblasts and normal small airway epithelial cells. Romidepsin, a HDAC inhibitor (HDACi), had the most favorable toxicity/efficacy ratios (TD. 50. /IC. 50. =57–580, depending on cell line). The only other HDACi in the panel of FDA-approved drugs (vorinostat) also ranked highly in the screen. Since newer HDACi's may have improved toxicity/efficacy ratios, we compared romidepsin and vorinostat with the three other HDACi's that are FDA-approved (belinostat, panobinostat, and valproic acid) plus one that is in clinical trials (entinostat). Romidepsin (C. max. /IC. 50. =36–360) and belinostat (C. max. /IC. 50. =14–20) reduced sarcosphere growth at clinically-achievable levels, in the presence or absence of MAP. Importantly, both romidepsin and belinostat were synergistic with MAP (BLISS scores=5–15). Propidium iodide staining showed that both romidepsin and MAP substantially induced cell death throughout the sarcospheres. Our results strongly support future studies to determine effects of romidepsin and belinostat on growth of lung metastases in vivo

Summary Statement. RANK is expressed in 18% of human osteosarcomas and is likely to provide additional prognostic information for clinical purposes in osteosarcoma patients at the time of diagnosis. Introduction. The receptor activator of nuclear factor kappa (RANK), a member of the tumor necrosis factor family, is activated by its ligand and regulates the differentiation of osteoclasts and dendritic cells. Local growth of osteosarcoma involves destruction of the host bone by osteoclasts and proteolytic mechanisms. Although prognosis of osteosarcoma has been improved by chemotherapy during the last decades, the problem of non responders and the lack of prognostic markers remains. It is the aim of this study to investigate the prognostic and predictive value of RANK expression in human osteosarcoma. Patients & Methods. The expression of RANK was examined immunohistochemically in biopsies of 43 patients (mean age 25.7 years) with high grade osteosarcoma and the results were correlated with histologic response to chemotherapy, disease free and overall survival. Tumors with more than 40% positive osteosarcoma cells were scored positive. Results. In 8 of 43 (18%) osteosarcoma specimens RANK expression could be dedected, the rest were negative. RANK expression showed a statistically significant correlation with overall survival of patients. 7/8 patients with RANK expressing tumours died, whereas only one in the negative group (88% in RANK positive tumours versus 37%; p<0.05). No significant difference was found when comparing RANK expression status with response to chemotherapy; 50% had a poor and 50% had a good response in RANK positive and 30,3% had a good and 69,7% had a bad response in RANK negative osteosarcomas. The appearance of metastases did not correlate with RANK expression status (37,5% metastases in RANK positive tumours versus 28,6% in negative). Discussion/Conclusion. In conclusion our findings suggest that RANK is likely to provide additional prognostic information for clinical purposes in osteosarcoma patients at the time of diagnosis

We undertook a study of the anti-tumour effects of hyperthermia, delivered via magnetite cationic liposomes (MCLs), on local tumours and lung metastases in a mouse model of osteosarcoma. MCLs were injected into subcutaneous osteosarcomas (LM8) and subjected to an alternating magnetic field which induced a heating effect in MCLs. A control group of mice with tumours received MCLs but were not exposed to an AMF. A further group of mice with tumours were exposed to an AMF but had not been treated with MCLs. The distribution of MCLs and local and lung metastases was evaluated histologically. The weight and volume of local tumours and the number of lung metastases were determined. Expression of heat shock protein 70 was evaluated immunohistologically. Hyperthermia using MCLs effectively heated the targeted tumour to 45°C. The mean weight of the local tumour was significantly suppressed in the hyperthermia group (p = 0.013). The mice subjected to hyperthermia had significantly fewer lung metastases than the control mice (p = 0.005). Heat shock protein 70 was expressed in tumours treated with hyperthermia, but was not found in those tumours not exposed to hyperthermia. The results demonstrate a significant effect of hyperthermia on local tumours and reduces their potential to metastasise to the lung

We evaluated the possible induction of a systemic immune response to increase anti-tumour activity by the re-implantation of destructive tumour tissue treated by liquid nitrogen in a murine osteosarcoma (LM8) model. The tumours were randomised to treatment by excision alone or by cryotreatment after excision. Tissue from the tumour was frozen in liquid nitrogen, thawed in distilled water and then re-implanted in the same animal. In addition, some mice received an immunological response modifier of OK-432 after treatment. We measured the levels of interferon-gamma and interleukin-12 cytokines and the cytotoxicity activity of splenocytes against murine LM8 osteosarcoma cells. The number of lung and the size of abdominal metastases were also measured. Re-implantation of tumour tissue after cryotreatment activated immune responses and inhibited metastatic tumour growth. OK-432 synergistically enhanced the anti-tumour effect. Our results suggest that the treatment of malignant bone tumours by reconstruction using autografts containing tumours which have been treated by liquid nitrogen may be of clinical value

Concomitant tumour resistance (CTR) is a unique phenomenon in which animals harbouring large primary tumours are resistant to the growth of smaller metastatic tumours by systemic angiogenic suppression. To examine this clinically, in ten patients with osteosarcoma, we investigated the effects of removal of the primary tumour on the development of pulmonary metastases, the systemic angiogenesis-inducing ability and the serum levels of several angiogenesis modulators. We found that removal of the primary tumour significantly elevated systemic angiogenesis-inducing ability in five patients who had post-operative recurrence of the tumour. Post-operative elevation of the angiogenesis-induced ability was suppressed by the addition of an angiogenic inhibitor, endostatin. Also, primary removal of the tumour decreased the serum levels of vascular endothelial growth factor and endostatin. These findings suggest, for the first time, the presence of CTR in patients with osteosarcoma for whom postoperative antiangiogenic therapy may be used to prevent the post-operative progression of micrometastases

Osteosarcoma (OS) is an aggressive bone malignancy with a high relapse rate despite combined treatment with surgery and multiagent chemotherapy. As for other cancers, OS-associated microenvironment may contribute to tumor initiation, growth, and metastasis. We consider mesenchymal stromal cells (MSC) as a relevant cellular component of OS microenvironment, and have previously found that the interaction between MSC and tumor cells is bidirectional: tumor cells can modulate their peripheral environment that in turn becomes more favourable to tumor growth through metabolic reprogramming (1). Stem-like cells were derived from HOS osteosarcoma cell line by using the spherogenic system (2). CSC isolated from HOS (HOS-CSC) were co-coltured with MSC isolated from bone marrow. Cell lysates and supernatants were collected for the analysis of RNA expression and of secreted cytokines, by Q-RT-PCR and specific ELISA assays, respectively. Here, we determined the effects of MSC on OS stemness and migration, two major features associated with recurrence and chemoresistance. Recruitment of MSC to the tumor environment leads to enhanced proliferation of OS stem cells, which increase the expression levels of TGFβ1. The latter, in turn, could be responsible for the activation of NF-kB genes and IL-6 secretion by MSC. Pro-tumorigenic effects of MSC, via IL-6, including induction of HOS-CSC migration and sphere growth, can be counteracted by IL-6 neutralizing antibody. The presence of MSC is also responsible for increased expression of adhesion molecules involved in intra- or extra-vasation. Stromal cells in combination with OS spheres exploit a vicious cycle where the presence of CSC stimulates mesenchymal cytokine secretion, which in turn increases stemness, proliferation, migration, and metastatic potential of CSC. Furthermore, for the first time we identified a novel OS stem cell marker, the Met proto-oncogene, that is frequently overexpressed and is pathogenetically relevant in OS (2 and 3). Altogether, our data corroborates the concept that a comprehensive knowledge of the interplay between tumor and stroma that also includes the stem-like fraction of tumor cells is needed to develop novel and effective anti-cancer therapies

Bone tumours may recur locally even after wide surgical excision and systemic chemotherapy. Local control of growth may be accomplished by the addition of cytostatic drugs such as methotrexate (MTX) to bone cement used to fill the defect after surgery and to stabilise the reconstructive prosthesis. We have studied the elution kinetics of MTX and its solvent N-methyl-pyrrolidone (NMP) from bone cement and their biological activities in five cell lines of osteosarcoma and in osteoblasts, and compared them with the effects of the parent compounds alone and in combination. Our findings show that MTX is released continuously over months at concentrations highly cytotoxic to osteosarcoma cells and suggest that the impregnated bone cement would be effective in the long term. Proliferating osteoblasts, however, were much less sensitive towards MTX. The dose-response relationship for NMP and experiments with MTX/NMP-mixtures show that the eluted concentrations of solvent are not toxic and do not influence the effects of MTX. We suggest that bone cement containing MTX dissolved in NMP releases the drug in a suitable and effective way and may be of value in the treatment of bone tumours

Metastatic osteosarcoma is seen in 10-20% of patients at initial presentation with the lung the most common site of metastasis. Historically, prognosis has been poor. We studied trends in survival in our small developed nation and aimed to identify correlations between the survival rate and three factors: newer chemotherapy, advances in radiological imaging and a more aggressive approach adopted by cardiothoracic surgeons for lung metastases. Our national bone tumour registry was used to identify patients at the age of 18 or under, who presented with metastatic disease at initial diagnosis between 1933 and 2006. There were 30 patients identified. Kaplan-Meier analysis was used to determine survival rates and univariate analysis was performed using the Cox regression proportional hazards model. Median survival has improved over the last 50 years; highlighted by the ‘Kotz’ eras demonstrating incremental improvement with more effective chemotherapy agents (p=0.004), and a current 5-year survival of 16%. Aggressive primary and metastatic surgery also show improving trends in survival. Three patients have survived beyond 5 years. The introduction of computerised tomography scanning has led to an increase in the prevalence of metastases at initial diagnosis. Metastatic osteosarcoma remains with a very poor prognostic factor, however, aggressive management has been shown to prolong survival

The glycolytic-based metabolism of cancers promotes an acidic microenvironment that is responsible for increased aggressiveness. However, the effects of acidosis on tumour metabolism have been almost unexplored, and the metabolic adaptation of cancer cells to acidosis has never been compared with the metabolic response of normal cells. In this study, to pinpoint for the first time the different metabolic profiles between osteosarcoma (OS) cells and normal human fibroblasts (Fb) under short-term acidosis, we used capillary electrophoresis with time-of-flight mass spectrometry (CE-TOFMS). We also screened alterations of the epigenetic profiles – DNA methylation and histone acetylation – of OS cells and compared it with those of normal Fb. Using CE-TOFMS, we observed a significant metabolic difference associated with glycolysis repression (dihydroxyacetone phosphate), increase of amino acid catabolism (phosphocreatine and glutamate) and urea cycle enhancement (arginino succinic acid) in OS cells compared with normal Fb. Noteworthy, metabolites associated with chromatin modification, like UDP-glucose and N. 8. -acetylspermidine, decreased more in OS cells than in normal Fb. Further, combined bisulfite restriction analysis (COBRA) and acetyl-H3 immunoblotting indicated an epigenetic stability in OS cells than in normal Fb, and OS cells were more sensitive to an HDAC inhibitor under acidosis than under neutral condition. Our data suggest that acidosis promotes a metabolic reprogramming that can contribute to the epigenetic maintenance under acidosis only in OS cells, and then the acidic microenvironment should be considered for future therapeutic approaches. The application of epigenetic modulators will be able to become an effectively therapeutic option to selectively target malignancies under the acidic microenvironment

Osteosarcoma (OS) is a highly malignant primary tumor frequently occurring in children and adolescents. The mainstay of therapy is neoadjuvant chemotherapy and surgical removal of the lesion yielding a 50–70% of 5-year survival rate. Unfortunately, chemotherapy is currently unable to induce complete tumor necrosis leaving residual tumor cells free to metastasize or recidivate, thus resulting in a 30% mortality. The major limitation in those patients is the development of multidrug resistance (MDR) and the low water solubility of drugs such as Paclitaxel (PTX) that is in fact not included in the majority of chemotherapy protocols for OS treatment. We thus hypothesized to prevent the emergence of MDR and obtain significant tumor reduction, by engineering innovative nanoparticles (NPs) able to vehiculate the PTX and induce a dual synergic action: the cytostatic effect of PTX and the cytotoxicity generated by reactive oxygen species produced from light triggered photoactivation (PDT) of Chlorin e6 photosensitizer. To further improve the efficacy and reduce the side effects of NPs systemic administration, Mesenchymal Stromal Cells (MSC) are used as a “Trojan horse” to deliver the NPs directly to tumor cells, taking advantage of MSC ability to selectively recognize and efficiently engraft in OS tumor stroma. HSA were conjugated with photosensitizer Ce6 and the functionalized protein was used to produce PTX loaded nanoparticles through desolvation technique and drug-induced protein self-assembly (PTX-Ce6@HSA NP). Human MSC lines, isolated from the Bone marrow (BM) of different donors, were then loaded with different dosages of nanoparticles and their ability to internalize and transport the NPs, migrate and induce cytotoxic ROS upon light treatment were tested in in vitro cultures. Preliminary results showed that MSC efficiently internalize PTX-Ce6@HSA NPs and the photosensitizer Ce6 remains active inside the cells for at least 3 days after loading. Electron microscopy performed onto loaded MSC showed that NPs internalization take places via clathrin mediated transport, whereas HPLC analysis demonstrated a release kinetics of PTX mediated by exocytosis. Finally, PTX-Ce6@HSA NPs loaded MSC co-cultured with the OS tumor cell line SaOS-2 showed a significant tumor cell growth reduction. So fare, advances in drug delivery have failed to produce specific tool to improve the overall survival of OS patients. However, given our preliminary in vitro data we believe that the proposed multimodal therapy will minimize the side effects of the systemic chemotherapy and enhance the efficacy through the synergic effect of PTX and PDT. In the future, our strategy could be intended as an innovative co-adjuvant approach for OS treatment to be performed right before surgery to eliminate residual tumors cells after tumor mass removal

Residual tumor cells left in the bone defect after malignant bone tumor resection can result in local tumor recurrence and high mortality. Therefore, ideal bone filling materials should not only aid bone reconstruction or regeneration, but also exert local chemotherapeutic efficacy. However, common bone substitutes used in clinics are barely studied in research for local delivery of chemotherapeutic drugs. Here, we aimed to use facile manufacturing methods to render polymethylmethacrylate (PMMA) cement and ceramic granules suitable for local delivery of cisplatin to limit bone tumor recurrence. Porosity was introduced into PMMA cement by adding 1-4% carboxymethylcellulose (CMC) containing cisplatin, and chemotherapeutic activity was rendered to two types of granules via adsorption. Then, mechanical properties, porosity, morphology, drug release kinetics, ex vivo reconstructive properties of porous PMMA and in vitro anti-cancer efficacy against osteosarcoma cells were assessed. Morphologies, molecular structures, drug release profiles and in vitro cytostatic effects of two different drug-loaded granules on the proliferation of metastatic bone tumor cells were investigated. The mechanical strengths of PMMA-based cements were sufficient for tibia reconstruction at CMC contents lower than 4% (≤3%). The concentrations of released cisplatin (12.1% and 16.6% from PMMA with 3% and 4% CMC, respectively) were sufficient for killing of osteosarcoma cells, and the fraction of dead cells increased to 91.3% within 7 days. Functionalized xenogeneic granules released 29.5% of cisplatin, but synthetic CaP granules only released 1.4% of cisplatin over 28 days. The immobilized and released cisplatin retained its anti-cancer efficacy and showed dose-dependent cytostatic effects on the viability of metastatic bone tumor cells. Bone substitutes can be rendered therapeutically active for anticancer efficacy by functionalization with cisplatin. As such, our data suggest that multi-functional PMMA-based cements and cisplatin-loaded granules represent viable treatment options for filling bone defects after bone tumor resection

Osteosarcoma and other types of bone cancers often require bone resection, and backfill with cement. A novel silorane-based cement without PMMA's drawbacks, previously developed for dental applications, has been reformulated for orthopedic use. The aim of this study is to assess each cement's ability to elute doxorubicin, maintain its potency, and maintain suitable weight-bearing strength. The silorane-based epoxy cement was synthesized using a platinum-based Lamoreaux's catalyst. Four groups of cement were prepared. Two PMMA groups, one without any additives, one with 200 mg of doxorubicin. Two silorane groups: one without any additive, one with doxorubicin, added so that the w% of drug into both cements were equal. Pellets 6 × 12 mm were used for testing (ASTM F451). n=10. Ten pellets from each group were kept dry. All others were placed into tubes containing 2.5 mL of PBS and stored at 37 °C. Elution from doxorubicin-containing groups were collected every day for 7 days, with daily PBS changeout. Antibiotic concentrations were determined via HPLC. Compressive strength and compressive modulus of all groups were determined for unsoaked specimens, and those soaked for 7 and 14 days. MTT assays were done using an MG63 osteosarcoma cell line. Both cements were able to elute doxorubicin over 7 days in clinically-favorable quantities. For PMMA samples, the incorporation of doxorubicin was shown to significantly affect the compressive strength and modulus of the samples (p<0.01). Incorporation of doxorubicin into silorane had no significant effect on either (p>.05). MTT assays indicated that doxorubicin incorporated into the silorane cement maintained its effectiveness whereas that into PMMA did not. At the dosing used, both cements remained above the 70 MPa. Both PMMA and silorane-based cements can deliver doxorubicin. Doxorubicin, however, interacts chemically with PMMA, inhibiting polymerization and lowering the chemotherapeutic's effectiveness

Bone tissue is known to possess an intrinsic regeneration potential. However, in cases of major injury, trauma, and disease, bone loss is present, and the regeneration potential of the tissue is often impaired. The process of bone regeneration relies on a complex interaction of molecules. MicroRNAs (miRNA) are small, non-coding RNAs that inhibit messenger RNAs (mRNA). One miRNA can inhibit several mRNAs and one mRNA can be inhibited by several miRNAs. Functionally, miRNAs regulate the entire proteome via the local inhibition of translation. In fact, miRNA modulation has been shown to be involved in several musculoskeletal diseases. 1. In those pathologies, they modulate the transcriptional activity of mRNAs important for differentiation, tissue-specific activity, extracellular matrix production, etc. Because of their function in inhibiting translation, miRNAs are being researched in many diseases and are already being used for interventional treatment. 2. Bone tissue and its related conditions have been widely investigated up to this day. 1,3. This talk will focus on the relevancy of miRNAs to bone tissue, its homeostasis, and disease. After, examples will be given of how miRNAs can be used in bone regeneration and diseases such as osteoporosis and osteosarcoma. The use of miRNAs in both, detection and therapy will be discussed

Introduction. Vascularized fibular grafting following tumor resection is an essential treatment option in limb salvage surgery. This study aimed to assess the surgical and oncological outcomes of patients treated in Denmark between 2010 and 2022. Method. We present a retrospective review of a national cohort comprising 27 patients. The indications were 13 cases of Ewing sarcoma, 12 cases of osteosarcoma, and 2 cases of giant cell tumor. The median age at surgery was 16 years (range: 2-39), and the median follow-up was 82 months (range: 12-138). Patients were analyzed overall and stratified into upper and lower extremity groups based on tumor location. Result. The primary rate of graft union was 63%, and after secondary procedures, the overall rate of graft union was 67%, with a median time to union of 13 months (range: 7-29). The reoperation rate was 74%, while the rate of limb salvage was 93%, with two patients undergoing amputation during follow-up. The 5-year overall survival rate was 81% (95% CI: 61-92). Patients with upper extremity tumors were more likely to attain graft union (92% vs. 47%, p=0.02) and less likely to undergo multiple reoperations (17% vs 60%, p=0.047) compared to patients with lower extremity tumors. Conclusion. Vascularized fibula grafting remains a valuable option in limb salvage surgery with acceptable long-term outcomes. However, especially in lower extremity cases, a low rate of graft union and multiple reoperations are to be expected