Injectable hydrogel allows for sustained delivery of growth factor resulting in spinal mediated learning after injury.

No abstract

Successful clinical translation of mesenchymal stem cell (MSC) based therapies for cartilage repair will likely require the implementation of standardized protocols and broadly applicable tools that facilitate comparisons among cell types and chondroinduction methods. The present study investigated the utility of recombinant lentiviral reporter vectors as reliable tools for comparing chondrogenic potential among primary cell populations and distinguishing cellular-level variations of chondrogenic activity in widely used three-dimensional (3D) culture systems. Primary equine MSCs and chondrocytes were transduced with vectors containing combinations of fluorescent and luciferase reporter genes under constitutive cytomeglavirus (CMV) or chondrocyte-lineage (Col2) promoters. Reporter activity was measured by fluorescence imaging and luciferase assay. In 3D cultures of MSC aggregates and polyethylene glycol-hyaluronic acid (PEG-HA) hydrogels, transforming growth factor beta 3 (TGF-β3)-mediated chondroinduction increased Col2 reporter activity, demonstrating close correlation with histology and mRNA expression levels of COL2A1 and SOX9. Comparison of chondrogenic activities among MSC populations using a secretable luciferase reporter revealed enhanced chondrogenesis of bone marrow-derived MSCs relative to MSC populations from synovium and adipose tissues. A dual fluorescence reporter – enabling discrimination of highly chondrogenic (Col2-GFP) cells within an MSC population (CMV-tdtomato) – revealed marked heterogeneity in differentiating aggregate cultures, and identified chondrogenic cells in chondrocyte-seeded PEG-HA hydrogels after 6 weeks in a subcutaneous implant model – indicating stable, long-term reporter expression in vivo. These results suggested that lentiviral reporter vectors may be used to address fundamental questions regarding chondrogenic activity in chondroprogenitor cell populations and accelerate clinical translation of cell-based cartilage repair strategies.

No abstract

2016-11-03T14:11:40

Purpose: Several in vivo models have been developed to validate and analyze biomaterials for the treatment of damaged cartilage. Preclinical models are well represented by large animals, especially ovine and swine models. However, in such models there is a genetic heterogeneity and a need of high number of animals to reach statistical power. In addition, their housing and maintenance is extremely expensive. Murine and laprine animal models are powerful alternatives to bypass these limitations, but reduced size and spontaneous cartilage healing limit their use. The aim of this work was to develop an ectopic screening in vivo model that would provide a tool to validate different materials or cell treatments before large animals studies. This ectopic model should provide a chondrogenic environment to analyze in a simpler and faster way the typical processes that developed in a normal or injured joint. Methods: Osteochondral biopsies were harvested from swine knee joints of 6 mm diameter wide and 4 mm high (N ¼ 10). The samples received a four mm diameter full chondral injury without disturbing the subchondral bone. Osteochondral plugs (OC) were implanted subcutaneously into seven weeks old immunodeficient Rag2 mice (Balb/cA Rag2-/-gC-/-), three OC plugs per animal. Five groups were created, n ¼ 2 per group: Group 1, OC plugs receiving fibrin implants; Group 2, OC plugs receiving chondrocytes embedded in fibrin, Group 3, plugs receiving human chondrocytes embedded in fibrin plus 60 ng of TGFb; Group 4, OC plugs receiving a mix of human bone marrow mesenchymal stem cells (BMSCs) and human chondrocytes (80:20) embedded in fibrin and; Group 5, OC plugs receiving a mix of BMSCs and chondrocytes (80:20) in fibrin plus 60 ng of TGFb. Human chondrocytes were isolated from healthy areas of femoral condyles of OA patients receiving a total knee replacement. BMSCs were isolated from bone marrow aspirates from OA patients. Animals were housed after the surgery for 6 weeks. Later, implants were evaluated by histology and immunohistochemistry. Results: All the implanted OC plugs showed neo-vascularization and maintained their chondral and bone vitality after 6 weeks of implantation. Active remodeling of the subchondral bone in close contact with cartilage was detected, although not on the distant part of the plugs. The articular cartilage of the Group 1 did not show any spontaneous repair. Comparing the different cell-based treatments, the best histological and immunohistological results were obtained in Group 3 with detection of GAG and type II collagen neo-synthesis in the implant zone ( Figure 1). Conclusions: With this proof of concept we validated a feasible in vivo model to evaluate new cell therapies and biomaterials. With this innovative ectopic implantation model, it is possible to assess biomaterials and cells in an osteochondral environment minimizing the use of expensive and valuable large animals.Purpose: Damaged cartilage is incapable of self-repair and continues to be a significant clinical challenge. Articular car...