Advances in Meniscal Tissue Engineering

Abstract

SUMMARYInjuries and lesions to the meniscal cartilage of the knee joint are common. As a result of its limited regenerative capacity, early degenerative changes to the articular surface frequently occur, resulting in pain and poor function. Currently available surgical interventions include repair of tears, and partial and total meniscectomy but the results are inconsistent and often poor. Interest in the field of meniscal tissue engineering with the possibilities of better treatment outcomes has grown in recent times. Current research has focused on the use of mesenchymal stem cells, fibrochondrocytes, meniscal derived cells and fibroblast-like synoviocytes in tissue engineering. Mesenchymal stem cells are multipotent cells that have been identified in a number of tissues including bone marrow and synovium. Current research is aimed at defining the correct combination of cytokines and growth factors necessary to induce specific tissue formation and includes transforming growth factor-β (TGF-β), Platelet Derived Growth Factor (PDGF) and Fibroblast Growth Factor 2 (FGF2). Scaffolds provide mechanical stability and integrity, and supply a template for three-dimensional organization of the developing tissue. A number of experimental and animal models have been used to investigate the ideal scaffolds for meniscal tissue engineering. The ideal scaffold for meniscal tissue engineering has not been identified but biodegradable scaffolds have shown the most promising results. In addition to poly-glycolic acid (PGA) and poly-lactic acid (PLLA) scaffolds, new synthetic hydrogels and collagen sponges are also being explored. There are two synthetic meniscal implants currently in clinical use and there are a number of clinical trials in the literature with good short-and medium-term results. Both products are indicated for segmental tissue loss and not for complete meniscal replacement. The long-term results of these implants are unknown and we wait to see whether they will be proved to have benefits in delaying arthritic change and chondral damage.

Nontraditional Modification to Articular Cartilage

“…Recent evidence suggests that platelet-derived growth factor (PDGF) has a possible place in cartilage repair based on its role in wound healing and stimulation of ECM proliferation in bone growth. [43][44][45][46] Multiple animal studies have shown that PDGF has an excellent safety profile when used in isolation. PDGF has had an increasingly prominent role in research and media as in vivo use of PDGF remains largely within the context of PRP.…”

Assessment of Fibrin‐Based Hydrogels Containing a Fibrin‐Binding Peptide to Tune Mechanical Properties and Cell Responses

“…Thus, they exhibit maximum spreading on nonlinear substrates, even despite low elastic moduli that would otherwise suggest a round shape. [26][27][28][29][30][31][32][33][34][35][36] Research over the past decades has shown that embryonic and adult stem cells are ideal cell sources for Tissue Engineering. In particular multipotent adult mesenchymal stem cells (MSC) can be readily isolated, expanded and transplanted from animal or human sources.…”

“…In addition, the degradation time is significantly decreased with no further need for fibrinolytic inhibitors, making these hydrogels advantageous for in vivo applications. [ 27 ] Other commonly used synthetic polymer additives include polylactide acid (PLA), [ 2 ] poly‐glycolic acid (PGA), [ 32 ] polycarprolactone (PCL), [ 2 ] and polyethylene glycol (PEG), [ 3–6 – 27 ] as well as PEG‐based microgels with superparamagnetic iron oxide. [ 33–35 ]…”

“…Thus, they exhibit maximum spreading on nonlinear substrates, even despite low elastic moduli that would otherwise suggest a round shape. [ 26–36 ]…”

Structural Mimetic Silk Fiber-Reinforced Composite Scaffolds Using Multi-Angle Fibers

“…Circumferential fibers are predominant and occupy the deep zone. Radial and random fibers are found in the lamellar zone and random fibers are scattered in the superficial zone …”