G. Desando

Bipolar Fresh Osteochondral Allograft of the Ankle

Background: Severe post-traumatic ankle arthritis poses a reconstructive challenge in the young and active patient. Bipolar fresh osteochondral allograft (BFOA) may represent an intriguing alternative to arthrodesis and prosthetic replacement. The aim of this study was to describe a lateral trans-malleolar technique for BFOA, and to evaluate the results in a case series. Materials and Methods: From 2004 to 2006, 32 patients, mean age of 36.8 ± 8.4 years, affected by ankle arthritis underwent BFOA with a mean followup of 31.2 months. The graft was prepared by specifically designed jigs, including the talus and the tibia with the medial malleolus. The host surfaces were prepared by the same jigs through a lateral approach. The graft was placed and fixed with twist-off screws. Patients were evaluated clinically and radiographically at 2, 4, and 6 month after operation, and at a minimum 24 months followup. A biopsy of the grafted areas was obtained from 7 patients at 1-year followup for histological and immunohistochemical examination. Results: Preoperative AOFAS score was 33.1 ± 10.9 and postoperatively 69.5 ± 19.4 (p < 0.0005). Six failures occurred. Cartilage harvests showed hyaline-like histology with a normal collagen component but low proteoglycan presence and a disorganized structure. Samples were positive for MMP-1, MMP-13 and Capsase-3. Conclusion: The use of BFOA represents an intriguing alternative to arthrodesis or arthroplasty. We believe precise allograft sizing, stable fitting and fixation and delayed weightbearing were key factors for a successful outcome. Further research regarding the immunological behavior of transplanted cartilage is needed. Level of Evidence: IV, Retrospective Case Series

Autologous Bone Marrow Concentrate in a Sheep Model of Osteoarthritis: New Perspectives for Cartilage and Meniscus Repair.

INTRODUCTION Cell-based therapies are becoming a valuable tool to treat osteoarthritis (OA). This study investigated and compared the regenerative potential of bone marrow concentrate (BMC) and mesenchymal stem cells (MSC), both engineered with Hyaff(®)-11 (HA) for OA treatment in a sheep model. METHODS OA was induced via unilateral medial meniscectomy. Bone marrow was aspirated from the iliac crest, followed by concentration processes or cell isolation and expansion to obtain BMC and MSC, respectively. Treatments consisted of autologous BMC and MSC seeded onto HA. The regenerative potential of bone, cartilage, menisci, and synovia was monitored using macroscopy, histology, immunohistochemistry, and micro-computed tomography at 12 weeks post-op. Data were analyzed using the general linear model with adjusted Sidaks multiple comparison and Spearmans tests. RESULTS BMC-HA treatment showed a greater repair ability in inhibiting OA progression compared to MSC-HA, leading to a reduction of inflammation in cartilage, meniscus, and synovium. Indeed, the decrease of inflammation positively contributed to counteract the progression of fibrotic and hypertrophic processes, known to be involved in tissue failure. Moreover, the treatment with BMC-HA showed the best results in allowing meniscus regeneration. Minor healing effects were noticed at bone level for both cell strategies; however, a downregulation of subchondral bone thickness (Cs.Th) was found in both cell treatments compared to the OA group in the femur. CONCLUSION The transplantation of BMC-HA provided the best effects in supporting regenerative processes in cartilage, meniscus, and synovium and at less extent in bone. On the whole, both MSC and BMC combined with HA reduced inflammation and contributed to switch off fibrotic and hypertrophic processes. The observed regenerative potential by BMC-HA on meniscus could open new perspectives, suggesting its use not only for OA care but also for the treatment of meniscal lesions, even if further analyses are necessary to confirm its healing potential at long-term follow-up.

Novel nano-composite biomimetic biomaterial allows chondrogenic and osteogenic differentiation of bone marrow concentrate derived cells

In clinical orthopedics suitable materials that induce and restore biological functions together with the right mechanical properties are particularly needed for the regeneration of osteochondral lesions. For this purpose, the ideal scaffold should possess the right properties with respect to degradation, cell binding, cellular uptake, non-immunogenicity, mechanical strength, and flexibility. In addition, it should be easy to handle and serve as a template for chondrocyte and bone cells guiding both cartilage and bone formation. The aim of the present study was to estimate the chondrogenic and osteogenic capability of bone marrow concentrated derived cells seeded onto a novel nano-composite biomimetic material. These properties have been evaluated by means of histological, immunohistochemical and electron microscopy analyses. The data obtained demonstrated that freshly harvested cells obtained from bone marrow were able, once seeded onto the biomaterial, to differentiate either down the chondrogenic and osteogenic pathways as evaluated by the expression and production of specific matrix molecules. These findings support the use, for the repair of osteochondral lesions, of this new nano-composite biomimetic material together with bone marrow derived cells in a “one step” transplantation procedure.

Repair Potential of Matrix-Induced Bone Marrow Aspirate Concentrate and Matrix-Induced Autologous Chondrocyte Implantation for Talar Osteochondral Repair: Patterns of Some Catabolic, Inflammatory, and Pain Mediators

Objective The low regenerative potential of cartilage contributed to the development of different cell therapies aimed to improve the clinical outcome in young patients with Osteochondral Lesions of the Talus (OLT). This study is designed to assess the regenerative potential of autologous matrix-induced Bone Marrow Aspirate Concentrate (mBMAC) and matrix-induced Autologous Chondrocyte Implantation (mACI) evaluating, on a small number of osteochondral biopsies, the expression of some catabolic, inflammatory, and pain mediators. Design Twenty-two patients with OLT were analyzed in this study; 7 were treated with mACI and 15 with mBMAC. Informed consent was obtained from all the patients. Clinical assessments were performed pre-operatively and at 12, 24, and 36 months after surgery using the American Orthopedic Foot and Ankle Society (AOFAS). Histology and immunohistochemistry were used to assess cartilage repair at 24 months. Data were analyzed using non-parametric Wilcoxon-Mann-Whitney and Spearman tests. Results A remarkable improvement in AOFAS score was noticed for both treatments up to 36 months; however, patients treated with mACI reported the best AOFAS score. Various degrees of tissue remodeling were observed by histological analysis for both cell strategies. However, mBMAC treatment showed a higher expression of some fibrous and hypertrophic markers compared to mACI group. A mild positivity for nerve growth factor, as pain mediator, was noticed for both treatments.M Conclusions Our findings demonstrated the best histological and clinical results following mACI treatment since different fibrotic and hypertrophic features were evident in the mBMAC group at 24-month follow-up.

Ankle bipolar fresh osteochondral allograft survivorship and integration: Transplanted tissue genetic typing and phenotypic characteristics

BACKGROUND Fresh osteochondral allografts represent a treatment option for early ankle posttraumatic arthritis. Transplanted cartilage survivorship, integration, and colonization by recipient cells have not been fully investigated. The aim of this study was to evaluate the ability of recipient cells to colonize the allograft cartilage and to assess allograft cell phenotype. METHODS Seventeen ankle allograft samples were studied. Retrieved allograft cartilage DNA from fifteen cases was compared with recipient and donor constitutional DNA by genotyping. In addition, gene expression was evaluated on six allograft cartilage samples by means of real-time reverse transcription-polymerase chain reaction. Histology and immunohistochemistry were performed to support molecular observations. RESULTS Of fifteen genotyped allografts, ten completely matched to the host, three matched to the donor, and two showed a mixed profile. Gene expression analysis showed that grafted cartilage expressed cartilage-specific markers. CONCLUSIONS The rare persistence of donor cells and the prevailing presence of host DNA in retrieved ankle allografts suggest the ingrowth of recipient cells into the allograft cartilage, presumably migrating from the subchondral bone, in accordance with morphological findings. The expression of chondrogenic markers in some of the samples argues for the acquisition of a chondrocyte-like phenotype by these cells. CLINICAL RELEVANCE To our knowledge, this is the first report describing the colonization of ankle allograft cartilage by host cells showing the acquisition of a chondrocyte-like phenotype.

Three-Dimensional Bioprinting of Cartilage by the Use of Stem Cells: A Strategy to Improve Regeneration

Cartilage lesions fail to heal spontaneously, leading to the development of chronic conditions which worsen the life quality of patients. Three-dimensional scaffold-based bioprinting holds the potential of tissue regeneration through the creation of organized, living constructs via a “layer-by-layer” deposition of small units of biomaterials and cells. This technique displays important advantages to mimic natural cartilage over traditional methods by allowing a fine control of cell distribution, and the modulation of mechanical and chemical properties. This opens up a number of new perspectives including personalized medicine through the development of complex structures (the osteochondral compartment), different types of cartilage (hyaline, fibrous), and constructs according to a specific patient’s needs. However, the choice of the ideal combination of biomaterials and cells for cartilage bioprinting is still a challenge. Stem cells may improve material mimicry ability thanks to their unique properties: the immune-privileged status and the paracrine activity. Here, we review the recent advances in cartilage three-dimensional, scaffold-based bioprinting using stem cells and identify future developments for clinical translation. Database search terms used to write this review were: “articular cartilage”, “menisci”, “3D bioprinting”, “bioinks”, “stem cells”, and “cartilage tissue engineering”.

Short-Term Homing of Hyaluronan-Primed Cells: Therapeutic Implications for Osteoarthritis Treatment.

The evaluation of key factors modulating cell homing following injection can provide new insights in the comprehension of unsolved biological questions about the use of cell therapies for osteoarthritis (OA). The main purpose of this in vivo study was to investigate the biodistribution of an intra-articular injection of mesenchymal stromal cells (MSCs) and bone marrow concentrate (BMC) in a rabbit OA model and whether the additional use of sodium hyaluronate (HA) could modulate their migration and delay joint degeneration. OA was surgically induced in adult male New Zealand rabbits. A group of animals was used to test the biodistribution of labeled cells alone or with HA at 7 and 14 days to investigate cell migration. The efficacy of treatments was evaluated in other experimental groups at 2 months. Histology and immunohistochemistry for markers identifying anabolic and catabolic processes in the cartilage and meniscus, or macrophage subset population in the synovial membrane, were performed. Kruskal-Wallis test, followed by post hoc Dunns test, and Spearmans rank-order correlation method were used. MSCs and BMC preferentially migrate toward tissue areas showing OA features in the meniscus and cartilage and in detail near inflammatory zones in the synovial membrane. The combination with HA contributed to boost cell migration toward articular cartilage. In general, both labeled cells combined with HA were found near cell cluster and fissures in the cartilage and meniscus, respectively, and close to areas of synovial membrane showing mainly anti-inflammatory macrophages. A promotion of joint repair was observed at different levels for all treatments, although BMC-HA treatment resulted as the best strategy to support joint repair. This last, displayed a good protein expression of type II collagen in the cartilage, as well as the presence of anti-inflammatory macrophages in the synovial membrane at 2 months from the treatment. Studies tracking cell biodistribution indicate that priming progenitor cells with HA modulated cell homing favoring not only attachment but also their integration within articular cartilage.

505 CHONDROCYTE GENETIC TYPING IN MASSIVE FRESH OSTEOCHONDRAL ALLOGRAFT AT 18 MONTHS AFTER TRANSPLANTATION: ARE THE CELLS STILL FROM THE DONOR?

INTRODUCTION Early post-traumatic arthritis of the knee and ankle is a debilitating condition posing a reconstructive challenge for the young and active patient. Inevitable loosening of joint arthroplasty in a young active population has lead to the search for a biologic me thod of repair. Bipolar fresh osteochondral allograft (BFOA) repres ent a fascinating alternative to arthrodesis and prosthetic replaceme nt and, to date, the use of fresh osteochondral allografting to replace dama ged articular cartilage has been well documented . BFOA provide viable cartilage supported by an intac t subchondral bony structure which is progressively replaced by host b one over time . Nevertheless, little is known regarding cartilage b havior following transplantation and the survivorship of the transpl anted cartilage has not been fully investigated. Few reports exist claiming the long term survivorship of the donor chondrocytes and the inha bility of the host cells to colonize the cartilage layer . Aim of this study was to investigate the survivorsh ip of donor chondrocytes, the repopulation of the transplanted cartilage by host cells and the nature of these cells by genetic typing and mRNA expression analysis at 18 months follow up after transplantati on.

162 CHONDROCYTES FROM OSTEOARTHRITIS PATIENTS REVERT TO THEIR ORIGIN PHENOTYPE ONCE GROWN ONTO A HYALURONAN-BASED SCAFFOLD

or ovariectomy (OVX), and administered either vehicle or 30 mg/kg hPTH (1−34aa) by s.c. injection for 5 weeks, n = 10. Serum levels of osteocalcin and CTX-II were measured by specific ELISAs. Results: When stimulated with PTH, the cultured chondrocytes accumulated intracellular cAMP levels significantly (P< 0.003) in a dose-depend manner. The maximum concentration of PTH (100 nM) resulted in a 23fold increase compared with vehicle control. In the explants cultures of OA articular cartilage, a two-fold increase of PIINP was observed in the supernatant after PTH stimulation when compared to non-stimulated cartilage samples. Furthermore, 10 nM PTH increased incorporation of 35sulphate by 40% (p=0.002). The serum level of the bone turnover marker osteocalcin was significantly (p< 0.001) elevated in OVX animals that were PTH treated compared to sham and vehicle treated, while the level of serum cartilage degradation marker CTX-II decreased by 30% (p< 0.01). Conclusions: The current data strongly suggest that PTH, in addition to osteoblasts and bone turnover, also has direct anabolic effects on chondrocytes and cartilage. We have shown that PTH can not only avert but also facilitate cartilage generation in both in vitro and in vivo situations. Presented data indicate the potency of PTH and intrigues further investigation of PTH as a potential DMOAD.