Biomarkers of bone healing induced by a regenerative approach based on expanded bone marrow-derived mesenchymal stromal cells.

BACKGROUND: Safety and feasibility of a regenerative strategy based on the use of culture-expanded mesenchymal stromal cells (MSCs) have been investigated in phase 2 trials for the treatment of nonunion and osteonecrosis of the femoral head (ONFH). As part of the clinical study, we aimed to evaluate if bone turnover markers (BTMs) could be useful for predicting the regenerative ability of the cell therapy product. MATERIALS AND METHODS: The bone defects of 39 patients (nonunion: n = 26; ONFH: n = 13) were treated with bone marrow-derived MSCs, expanded using a clinical-grade protocol and combined with biphasic calcium phosphate before implantation. Bone formation markers, bone-resorption markers and osteoclast regulatory proteins were measured before treatment (baseline) and after 12 and 24 weeks from surgery. At the same time-points, clinical and radiological controls were performed to evaluate the bone-healing progression. RESULTS: We found that C-Propeptide of Type I Procollagen (CICP) and C-terminal telopeptide of type-I collagen (CTX) varied significantly, not only over time, but also according to clinical results. In patients with a good outcome, CICP increased and CTX decreased, and this trend was observed in both nonunion and ONFH. Moreover, collagen biomarkers were able to discriminate healed patients from non-responsive patients with a good diagnostic accuracy. DISCUSSION: CICP and CTX could be valuable biomarkers for monitoring and predicting the regenerative ability of cell products used to stimulate the repair of refractory bone diseases. To be translated in a clinical setting, these results are under validation in a currently ongoing phase 3 clinical trial.

Biological effects of metal degradation in hip arthroplasties.

Metals and metal alloys are the most used materials in orthopedic implants. The focus is on total hip arthroplasty (THA) that, though well tolerated, may be associated with local and remote adverse effects in the medium-long term. This review aims to summarize data on the biological consequences of the metal implant degradation that have been attributed predominantly to metal-on-metal (MoM) THA. Local responses to metals consist of a broad clinical spectrum ranging from small asymptomatic tissue lesions to severe destruction of bone and soft tissues, which are designated as metallosis, adverse reactions to metal debris (ARMD), aseptic lymphocytic vasculitis associated lesion (ALVAL), and pseudotumors. In addition, the dissemination of metal particles and ions throughout the body has been associated with systemic adverse effects, including organ toxicity, cancerogenesis, teratogenicity, and immunotoxicity. As proved by the multitude of studies in this field, metal degradation may increase safety issues associated with THA, especially with MoM hip systems. Data collection regarding local, systemic and long-term effects plays an essential role to better define any safety risks and to generate scientifically based recommendations.

Alpha-lipoic Acid After Median Nerve Decompression at the Carpal Tunnel: A Randomized Controlled Trial.

PURPOSE: The postoperative course of median nerve decompression in carpal tunnel syndrome may be associated with complications. The aim of this study was to explore the possible effects of alpha-lipoic acid (ALA) in the postoperative period after surgical decompression of the median nerve at the wrist. METHODS: We conducted a double-blind prospective, randomized, controlled trial. A total of 64 patients with proven carpal tunnel syndrome were enrolled and randomly assigned into 1 of 2 groups: group A (n = 32) patients had surgical decompression of the median nerve followed by ALA for 40 days, and group P (n = 32) patients had surgical decompression followed by placebo. The primary end point of the study was a comprehensive indicator of sensory and motor nerve conduction velocity (electrophysiology score) at 3 months after surgery, Other end points were static 2-point discrimination, Boston Carpal Tunnel score, presence or absence of pillar pain, and use of analgesics beyond the second postoperative day. RESULTS: Alpha-lipoic acid did not improve nerve conduction velocity or Boston Carpal Tunnel score significantly. However, a statistically significant reduction in the postoperative incidence of pillar pain was noted in the ALA group. In addition, static 2-point discrimination improved in both groups. CONCLUSIONS: Postoperative administration of ALA for 40 days after median nerve decompression may result in a lower incidence of pillar pain. This treatment is relatively well tolerated, which may support its value as standard postoperative supplementation after carpal tunnel decompression if further studies on larger samples confirm these preliminary findings. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

Mesenchymal progenitors expressing TRAIL induce apoptosis in sarcomas.

Sarcomas are frequent tumors in children and young adults that, despite a relative chemo-sensitivity, show high relapse rates with up to 80% of metastatic patients dying in 5 years from diagnosis. The real ontogeny of sarcomas is still debated and evidences suggest they may derive from precursors identified within mesenchymal stromal/stem cells (MSC) fractions. Recent studies on sarcoma microenvironment additionally indicated that MSC could take active part in generation of a supportive stroma. Based on this knowledge, we conceived to use modified MSC to deliver tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) targeting different sarcoma histotypes. Gene modified MSC expressing TRAIL were cocultured with different osteosarcoma, rhabdomyosarcoma, and Ewing's Sarcoma (ES) cell lines assessing viability and caspase-8 activation. An in vivo model focused on ES was then implemented considering the impact of MSC-TRAIL on tumor size, apoptosis, and angiogenesis. MSC expressing TRAIL induced significantly high apoptosis in all tested lines. Sarcoma death was specifically associated with caspase-8 activation starting from 8 hours of coculture with MSC-TRAIL. When injected into pre-established ES xenotransplants, MSC-TRAIL persisted within its stroma, causing significant tumor apoptosis versus control groups. Additional histological and in vitro studies reveal that MSC-TRAIL could also exert potent antiangiogenic functions. Our results suggest that MSC as TRAIL vehicles could open novel therapeutic opportunities for sarcoma by multiple mechanisms.

Effects of hypoxia on osteogenic differentiation of mesenchymal stromal cells used as a cell therapy for avascular necrosis of the femoral head.

BACKGROUND AIMS: Avascular necrosis of the femoral head (AVN) occurs as common result of various conditions or develops as a primary entity, with a high freqency in young adults. Because of its tendency toward osteoarthritis requiring total hip arthroplasty, alternative treatments are being advocated, including cell therapy with mesenchymal stromal cells (MSCs). Because osteonecrotic bone is a severely hypoxic tissue, with a 1-3% oxygen tension, the survival and function of multipotent cells is questionable. METHODS: In this study, the proliferative, immunophenotypic and osteogenic properties of bone marrow (BM)-derived MSCs from a clinical series of patients with AVN were evaluated under in vitro conditions mimicking the hypoxic milieu of AVN to verify the rationale for cell therapy. MSCs retrieved from the iliac crest (BM-MSC) were isolated, expanded and induced to osteogenic differentiation under a 2% pO2 atmosphere (hypoxia) in comparison with the standard 21% pO2 (normoxia) that is routinely used in cell culture assays. RESULTS: Both proliferation and colony-forming ability were significantly enhanced in hypoxia-exposed BM-MSCs compared with BM-MSCs under normoxia. The expression of bone-related genes, including alkaline phosphatase, Type I collagen, and osteocalcin was significantly increased under hypoxia. Moreover, mineral deposition after osteogenic induction was not hampered, but in some cases even enhanced under low oxygen tension. CONCLUSIONS: These findings support autologous cell therapy as an effective treatment to stimulate bone healing in the hypoxic microenvironment of AVN.

Prolonged exposure to hypoxic milieu improves the osteogenic potential of adipose derived stem cells.

Mesenchymal stem cells (MSC) have been widely used in orthopedics for several applications. Conventionally, MSC are maintained under 21% O2 which does not reflect the real O2 tension in vivo. Recently, it was reported that different O2 conditions can give different cellular responses. Here, we investigated whether prolonged exposure to hypoxia affects the osteogenic differentiation of adipose-derived stem cells (ASC). ASC from six individuals were cultured under "low" (2-3%) or "air" (21%) oxygen tensions, either without or with osteogenic stimuli. The effect of the O2 tension was evaluated on cell proliferation, surface antigens, stemness and bone-related genes expression, alkaline phosphatase activity (ALP), mineralization activity, and release of osteogenic growth factors. Without differentiating stimuli, hypoxia favored ASC proliferation, reduced the number of CD184+ and CD34+ cells, and preserved the expression of NANOG and SOX2. The combination of hypoxia and osteogenic medium induced a high proliferation rate, a rapid and more pronounced mineralization activity, a higher expression of genes related to the MSC differentiation, a higher release of mitogenic growth factors (bFGF, PDGF-BB), and the decrease in TGF-ß secretion, an inhibitor of the early stage of the osteoblast differentiation. We demonstrated that hypoxia acts dually, favoring ASC proliferation and the maintenance of the stemness in the absence of osteogenic stimuli, but inducing the differentiation in a bone-like microenvironment. In conclusion, prolonged cell culture in hypoxic microenvironment represents a proper method to modulate the stem cell function that may be used in several applications, for example, studies on bone pathophysiology or bone-tissue engineering.

V-ATPase is a candidate therapeutic target for Ewing sarcoma.

Suppression of oxidative phosphorylation combined with enhanced aerobic glycolysis and the resulting increased generation of protons are common features of several types of cancer. An efficient mechanism to escape cell death resulting from intracellular acidification is proton pump activation. In Ewing sarcoma (ES), although the tumor-associated chimeric gene EWS-FLI1 is known to induce the accumulation of hypoxia-induced transcription factor HIF-1α, derangements in metabolic pathways have been neglected so far as candidate pathogenetic mechanisms. In this paper, we observed that ES cells simultaneously activate mitochondrial respiration and high levels of glycolysis. Moreover, although the most effective detoxification mechanism of proton intracellular storage is lysosomal compartmentalization, ES cells show a poorly represented lysosomal compartment, but a high sensitivity to the anti-lysosomal agent bafilomycin A1, targeting the V-ATPase proton pump. We therefore investigated the role of V-ATPase in the acidification activity of ES cells. ES cells with the highest GAPDH and V-ATPase expression also showed the highest acidification rate. Moreover, the localization of V-ATPase was both on the vacuolar and the plasma membrane of all ES cell lines. The acidic extracellular pH that we reproduced in vitro promoted high invasion ability and clonogenic efficiency. Finally, targeting V-ATPase with siRNA and omeprazole treatments, we obtained a significant selective reduction of tumor cell number. In summary, glycolytic activity and activation of V-ATPase are crucial mechanisms of survival of ES cells and can be considered as promising selective targets for the treatment of this tumor.

Preparation method and growth factor content of platelet concentrate influence the osteogenic differentiation of bone marrow stromal cells.

BACKGROUND AIMS: An extensive debate about the clinical benefits of autologous platelet concentrates used as a treatment option for patients with orthopedic injuries is ongoing. The aim of this study was to determine whether different compositions of platelet concentrates may affect the osteogenic differentiation of bone marrow stromal cells (BMSC). METHODS: Pure platelet-rich plasma (P-PRP) and leukocyte-PRP (L-PRP) were characterized for platelet and leukocyte content. As an indicative marker of the delivery of growth factors (GFs), the release of basic fibroblast growth factor (bFGF) from platelet gel (PG) was measured at 1, 18, 48 and 72 h and at 7 d. The ability of different PGs to induce proliferation and differentiation of BMSC was evaluated by using bioactivity assays. RESULTS: The platelet recovery was significantly higher in L-PRP, either fresh or frozen. PGs derived from L-PRP and P-PRP showed significant differences in terms of bFGF release and biological activity. bFGF release was faster both in fresh and frozen L-PRP preparations. Moreover, L-PRP samples were able to induce a significantly higher proliferation of BMSC compared with P-PRP or PPP samples. Even though all PG preparations allowed the deposition of mineral nodules in BMSC cultures, the mineralization activity correlated significantly with bFGF levels. CONCLUSIONS: The biological activity of platelet concentrates differs according to preparation technique, which affects platelet and leukocyte content and GF availability. Because GF levels are not always optimal in subjects with defective bone healing, composition and bioactivity of PRP should be analyzed to test the reliability and potential effectiveness of the regenerative treatment.

A regenerative approach for bone repair in congenital pseudarthrosis of the tibia associated or not associated with type 1 neurofibromatosis: correlation between laboratory findings and clinical outcome.

BACKGROUND AND AIMS: Congenital pseudarthrosis of the tibia (CPT) is a rare orthopedic disease presenting spontaneous fractures that do not heal. The treatment of CPT is characterized by repeated surgical procedures that often fail, with the inevitable outcome of severe disability and amputation. We tested the hypothesis that CPT may benefit from regenerative strategies based on mesenchymal stromal cells (MSC) combined with platelet-rich fibrin (PRF) as a source of growth factors. The aim of the study was to verify whether laboratory testing to assess the osteogenic properties of MSC and the osteo-inductive activity of PRF correlated with the clinical outcome. METHODS: Ten patients affected by refractory CPT were treated by using MSC derived from the iliac crest (IC-MSC), PRF and lyophilized bone. In six patients, CPT was associated with type 1 neurofibromatosis (NF1). Biochemical, functional and molecular assays were performed to assess the intrinsic osteogenic potential of IC-MSC (cells cultured with fetal calf serum) and the osteo-inductive properties of PRF (cells cultured with autologous serum). RESULTS: Bone consolidation was obtained in three patients who had CPT and NF1. In these patients, the IC-MSC exposed to autologous serum were able to form mineral nodules in vitro, while the mineralizing ability was totally abrogated in patients with a poor clinical outcome. CONCLUSIONS: Cell therapy may be a useful tool for the treatment of refractory CPT because it increases the opportunity to achieve effective bone tissue regeneration. Our data suggest that the presence of pro-osteogenic growth factors is an essential requirement for bone healing.

IGF2 derived from SH-SY5Y neuroblastoma cells induces the osteoclastogenesis of human monocytic precursors.

The insulin-like growth factors 2 (IGF2) is a peptide hormone that binds to the insulin-like growth factor 1 receptor (IGF1R) and is abundantly stored in bone. IGF1R is deeply involved in the pathogenesis of many cancers that growth within bone and is also involved in osteoclast biology. Among different cell lines representative of osteolytic tumors, we found a very high expression of IGF2 in SH-SY5Y cells derived from neuroblastoma (NB). We previously showed that NB cells induce an osteolytic process through the Osteoprotegerin/RANKL/RANK and the canonical Wnt pathway system. Here, we hypothesized that NB promotes osteoclastogenesis also via IGF2. First, we demonstrated the presence of IGF1R on the osteoclast basolateral membrane, and we observed a cyclic IGF1R activation along with the differentiation process, also when induced by SH-SY5Y. Moreover, we found that IGF2 mRNA expression in SH-SY5Y cells was further increased when co-cultured with mesenchymal stromal cells, suggesting that IGF2 is important for NB interaction with the bone microenvironment. Finally, the treatment of SH-SY5Y cells with an anti-IGF2 siRNA or the addition of anti-IGF1R molecules impaired NB-induced osteoclastogenesis, even though the chemoattraction of monocytes by NB cells was unaffected. Our findings suggest that in IGF2-producing osteolytic tumors IGF1R is a good candidate for targeted therapies in combination with conventional drugs.

Ex vivo observation of human intervertebral disc tissue and cells isolated from degenerated intervertebral discs.

PURPOSE: Disc degeneration, and associated low back pain, are a primary cause of disability. Disc degeneration is characterized by dysfunctional cells and loss of proteoglycans: since intervertebral tissue has a limited capacity to regenerate, this process is at present considered irreversible. Recently, cell therapy has been suggested to provide more successful treatment of IVD degeneration. To understand the potential of cells to restore IVD structure/function, tissue samples from degenerated IVD versus healthy discs have been compared. METHODS: Discal tissue from 27 patients (40.17 ± 11 years) undergoing surgery for degenerative disc disease (DDD), DDD + herniation and congenital scoliosis, as controls, was investigated. Cells and matrix in the nucleus pulposus (NP) and annulus fibrosus (AF) were characterized by histology. AF- and NP-derived cells were isolated, expanded and characterized for senescence and gene expression. Three-dimensional NP pellets were cultured and stained for glycosaminoglycan formation. RESULTS: Phenotypical markers of degeneration, such as cell clusters, chondrons, and collagen disorganization were seen in the degenerate samples. In severe degeneration, granulation tissue and peripheral vascularization were observed. No correlation was found between the Pfirrmann clinical score and the extent of degeneration. CONCLUSION: The tissue disorganization in degenerate discs and the paucity of cells out of cluster/chondron association, make the IVD-derived cells an unreliable option for disc regeneration.

Enhancing osteoconduction of PLLA-based nanocomposite scaffolds for bone regeneration using different biomimetic signals to MSCs.

In bone engineering, the adhesion, proliferation and differentiation of mesenchymal stromal cells rely on signaling from chemico-physical structure of the substrate, therefore prompting the design of mimetic "extracellular matrix"-like scaffolds. In this study, three-dimensional porous poly-L-lactic acid (PLLA)-based scaffolds have been mixed with different components, including single walled carbon nanotubes (CNT), micro-hydroxyapatite particles (HA), and BMP2, and treated with plasma (PT), to obtain four different nanocomposites: PLLA + CNT, PLLA + CNTHA, PLLA + CNT + HA + BMP2 and PLLA + CNT + HA + PT. Adult bone marrow mesenchymal stromal cells (MSCs) were derived from the femur of orthopaedic patients, seeded on the scaffolds and cultured under osteogenic induction up to differentiation and mineralization. The release of specific metabolites and temporal gene expression profiles of marrow-derived osteoprogenitors were analyzed at definite time points, relevant to in vitro culture as well as in vivo differentiation. As a result, the role of the different biomimetic components added to the PLLA matrix was deciphered, with BMP2-added scaffolds showing the highest biomimetic activity on cells differentiating to mature osteoblasts. The modification of a polymeric scaffold with reinforcing components which also work as biomimetic cues for cells can effectively direct osteoprogenitor cells differentiation, so as to shorten the time required for mineralization.

Ultrasound-guided injection of platelet-rich plasma or cord blood platelet-rich plasma in nonunion: a randomized controlled trial.

Aim: To compare the ability of autologous platelet-rich plasma (PRP) and cord blood PRP (PRPc) to accelerate bone healing. Patients & methods: 71 patients with mechanically stable nonunion were treated weekly (3 consecutive weeks) with ultrasound-guided percutaneous injections of PRP or PRPc in a controlled randomized clinical trial. The primary outcome was healing (12 months) and secondary outcomes were radiological evolution (2 and 6 months) and changes in pain intensity (6 months). Results & conclusion: Bone consolidation was assessed over time without significant differences between PRP and PRPc treatment. In patients with persistent nonunion, pain perception decreased more after PRP treatment. PRPc appears to be a valid alternative when specific clinical conditions suggest avoiding the use of autologous blood products.

Although the regenerative capacity of bone tissue is well recognized, the fracture repair process may be impaired by unfavorable conditions resulting in delayed union or complete nonunion. In this scenario, the use of autologous blood derivates to accelerate bone healing has been proposed. The aim of this study was to compare the therapeutic efficacy of autologous platelet-rich plasma (PRP) and cord blood PRP (PRPc) in bone nonunion. PRPc contains high levels of cytokines and growth factors, has low immunogenicity and can be successfully stored until use. This study verified that bone consolidation was similar in PRP and PRPc treatments, thus supporting PRPc as a valid therapeutic option when clinical conditions discourage the use of autologous blood derivates.

Citrate Supplementation Restores the Impaired Mineralisation Resulting from the Acidic Microenvironment: An In Vitro Study.

Chronic metabolic acidosis leads to bone-remodelling disorders based on excessive mineral matrix resorption and inhibition of bone formation, but also affects the homeostasis of citrate, which is an essential player in maintaining the acid-base balance and in driving the mineralisation process. This study aimed to investigate the impact of acidosis on the osteogenic properties of bone-forming cells and the effects of citrate supplementation in restoring the osteogenic features impaired by the acidic milieu. For this purpose, human mesenchymal stromal cells were cultured in an osteogenic medium and the extracellular matrix mineralisation was analysed at the micro- and nano-level, both in neutral and acidic conditions and after treatment with calcium citrate and potassium citrate. The acidic milieu significantly decreased the citrate release and hindered the organisation of the extracellular matrix, but the citrate supplementation increased collagen production and, particularly calcium citrate, promoted the mineralisation process. Moreover, the positive effect of citrate supplementation was observed also in the physiological microenvironment. This in vitro study proves that the mineral matrix organisation is influenced by citrate availability in the microenvironment surrounding bone-forming cells, thus providing a biological basis for using citrate-based supplements in the management of bone-remodelling disorders related to chronic low-grade acidosis.

Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells.

The nonadherent (NA) population of bone-marrow-derived mononuclear cells (MNC) has been demonstrated to be a source of osteogenic precursors in addition to the plastic-adherent mesenchymal stromal cells (MSC). In the current study, two subpopulations of late adherent (LA) osteoprogenitors were obtained by subsequent replating of NA cells, and their phenotypic, functional, and molecular properties were compared with those of early adherent (EA) MSC. Approximately 35% of MNC were LA cells, and they acquired a homogeneous expression of MSC antigens later than EA cells. In EA-MSC, the alkaline phosphatase (ALP) activity increased significantly from time of seeding to the first confluence, whereas in LA cells it raised later, after the addition of mineralization medium. All subpopulations were able to produce type I collagen and to deposit extracellular matrix with organized collagen fibrils. The proportion of large colonies with more than 50% of ALP positive cells as well as the calcium content was higher in LA than in EA cells. Molecular analysis highlighted the upregulation of bone-related genes in LA-MSC, especially after the addition of mineralization medium. Our results confirm that bone marrow contains LA osteoprogenitors which exhibit a delay in the differentiation process, despite an osteogenic potential similar to or better than EA-MSC. LA cells represent a reservoir of osteoprogenitors to be recruited to gain an adequate bone tissue repair and regeneration when a depletion of the most differentiated component occurs. Bone tissue engineering and cell therapy strategies could take advantage of LA cells, since an adequate amount of osteogenic MSCs may be obtained while avoiding bone marrow manipulation and cell culture expansion.

Role of Citrate in Pathophysiology and Medical Management of Bone Diseases.

Citrate is an intermediate in the "Tricarboxylic Acid Cycle" and is used by all aerobic organisms to produce usable chemical energy. It is a derivative of citric acid, a weak organic acid which can be introduced with diet since it naturally exists in a variety of fruits and vegetables, and can be consumed as a dietary supplement. The close association between this compound and bone was pointed out for the first time by Dickens in 1941, who showed that approximately 90% of the citrate bulk of the human body resides in mineralised tissues. Since then, the number of published articles has increased exponentially, and considerable progress in understanding how citrate is involved in bone metabolism has been made. This review summarises current knowledge regarding the role of citrate in the pathophysiology and medical management of bone disorders.

Paracrine inhibition of osteoblast differentiation induced by neuroblastoma cells.

The aim of our study was to investigate whether the defective function of osteogenic cells induced by neuroblastoma might play a role in the development of skeletal metastases. This mechanism has been extensively demonstrated for multiple myeloma, in which the blockage of osteoblast differentiation has been ascribed to the inhibitors of canonical Wingless pathway (Wnt), namely Dickkopf 1 (Dkk1). Our purpose was to verify if neuroblastoma cells derived from bone marrow metastases (SH-SY5Y, LAN1) or primaries (NB100, CHP212) hamper the differentiation of mesenchymal stem cells (hMSCs) into osteoblasts in a paracrine manner, and to test whether this ability depends on Dkk1 activity. We found that all neuroblastoma cells increased the proliferation of hMSCs collected from pediatric-aged donors, with a corresponding decrease in osteoblast differentiation markers, including alkaline phosphatase (ALP), analyzed as gene expression, enzymatic activity and number of ALP-positive colony forming units, osteoprotegerin (OPG) release, OPG and osteocalcin gene-expression. Dkk1 mRNA and protein were detectable in all cell lines, and the use of neutralizing anti-Dkk1 antibody reversed the effects induced by SH-SY5Y cells. Taken together, our results confirm that neuroblastoma hinders osteoblastogenesis, and that Dkk1 release seems to play a crucial role in blocking the differentiation of osteoprogenitor cells, though the ability to promote osteoclast activation remains an essential requirement for the development of skeletal metastases. Finally, our findings suggest that strategies regulating Wnt signaling and Dkk1 activity could be considered for adjuvant therapies in neuroblastoma metastasizing to the skeleton.

Increased osteoclast activity is associated with aggressiveness of osteosarcoma.

Osteosarcoma (OS) is a highly malignant primary skeletal tumor with a striking tendency to rapidly destroy the surrounding bone and metastasize, since metastases are frequently present at clinical onset. The basis for the aggressiveness of this tumor is largely unknown. However, recent studies in in vivo models indicate that the anti-osteolytic drugs, bisphosphonates, can inhibit the tumor local expansion and the formation of metastases. We further investigated the association between the presence of active osteoclasts and the aggressiveness of OS. We evaluated the presence of osteoclasts and the mRNA of different osteoclast-related genes in tumor biopsies from 16 OS patients and in three OS cell lines and the serum levels of bone resorption markers in the same series and in 28 other patients. Tumor-associated osteoclasts were found in 63 and 75% of cases by histological and mRNA analysis. Among different serum markers, only MMP-9 was significantly higher in OS cases (p=0.0001), whereas TRACP 5b was significantly higher in metastatic patients compared to nonmetastatic patients (p=0.0509). Serum TRACP 5b was significantly correlated to serum NTX (p<0.0001) and cathepsin K mRNA in tumor tissues (p=0.0153). In 8 patients we also analyzed TRACP 5b serum level at follow-up and we verified a significant decrease of TRACP 5b after primary tumor removal (p=0.0117). In conclusion, tumor-infiltrating osteoclasts are frequently found in OS and increased serum TRACP 5b levels and the presence of active osteoclast at primary sites were positively associated with tumor aggressiveness.

Sensitivity to implant materials in patients with total knee arthroplasties.

Materials used for total knee arthroplasty (TKA), may elicit an immune response whose role in the outcome of the arthroplasty is still unclear. The aim of this study was to evaluate the frequency of sensitization in patients who had undergone TKA, and the clinical impact of this event on the outcome of the implant. Ninety-four subjects were recruited, including 20 patients who had not yet undergone arthroplasty, 27 individuals who had a well-functioning TKA, and 47 patients with loosening of TKA components. Sensitization was detected by using patch testing including haptens representative of cobalt-based alloys (CoCrMo), titanium-based alloys (TiAlV), and bone cements. The frequency of positive skin reactions to metals increased significantly after TKA, either stable or loosened (No Implant 20%; Stable TKA 48.1%, p=0.05; Loosened TKA 59.6%, p=0.001, respectively). We found a higher frequency of positive patch testing to vanadium in patients who had a Stable TKA with at least one TiAlV component (39.1%, p=0.01). The medical history for metal allergy seems to be a risk factor, because the TKA failure was fourfold more likely in patients who had symptoms of metal hypersensitivity before TKA. The prognostic value was supported by survival analysis, because in these individuals the outcome of the implant was negatively influenced (the logrank test Chi square 5.1, p=0.02). This study confirms that in patients with a TKA the frequency of positive patch testing is higher than in the normal population, although no predictive value is attributable to the sensitization because patch testing was not able to discriminate between stable and loose implants. On the contrary, the presence of symptoms of metal allergy before implantation should be taken into account as a potential risk factor for TKA failure.

Biocompatibility of poly(D,L-lactide-co-glycolide) nanoparticles conjugated with alendronate.

Nanoparticles made of a conjugate of poly(D,L-lactide-co-glycolide) with alendronate (PLGA-ALE NPs), were prepared by emulsion/solvent evaporation technique. The conjugation yield, determined by MALDI TOF analysis, was 30-35%. PLGA-ALE NPs size, evaluated by photon correlation spectroscopy, was 198.7+/-0.2 nm. Haemocompatibility studies using different concentrations of PLGA-ALE NPs did not show any significant effect on haemolysis, leukocyte number, platelet activation, APTT and complement consumption, in comparison with blood incubated with phosphate buffered saline (PBS). A significant reduction of the prothrombin activity was demonstrated after incubation with 560 microg/ml of PLGA-ALE NPs; a significant increase was observed at the highest dilutions. The viability of human umbilical vein endothelial cells and bone marrow stromal cells (BMSC), evaluated through the neutral red test, was not affected by PLGA-ALE NPs. There were no significant differences in cell-associated alkaline phosphatase between BMSC incubated with PLGA-ALE NP- and PBS-added media. These results demonstrated that PLGA-ALE NPs had an acceptable degree of blood compatibility and were not cytotoxic; therefore, they may be considered suitable for intravenous administration.