Enhanced Cell Sheet Technology for Cartilage Repair

INTRODUCTION Cartilage is one of the most important bodily components in allowing one to walk painlessly. It is the connective tissue in your joints, providing smooth articulations and minimalizing friction between bones. Injuries to this tissue are very common and can be detrimental if not treated, due to its lack of intrinsic healing ability. There exist various known causes of cartilage injury, including joint dislocation, ligament tear, fall/impact, infection, and inflammation [1]. Osteoarthritis is the most common cartilage defect, afflicting approximately 27 million Americans today [2]. It is a degenerative disease seen most prevalently in elderly, obese, and former athletes due to excessive wear and tear on the joints. Currently, there are several techniques being used to reduce the impacts of defective cartilage; however, they all have shortcomings. Surgical intervention, for instance, whether that be grafting, microfracture, or injection, all expose patients to the risk of rejection, infection, and deterioration [2]. Ideally, an implant should consist of the patient’s own cells/tissue to reduce these risks. Autologous Chondrocyte Implantation (ACI) is a procedure that uses the patient’s own cells, expands them in vitro and then implants the new cartilage back into the body. Though this is an improvement from most surgical techniques, contamination and lack of cell number still limit this technique’s success [3]. Further advancements to the field of cartilage regeneration can be seen in the research currently be conducted by several groups in Japan. They hypothesized that layering sheets of mesenchymal stem cells (MSCs) will increase the rate and ability of differentiation into chondrocyte cells [4], [5]. However, none of these groups were able to obtain constructs that expressed mechanical properties suitable for implantation after chondroinduction.