Stem Cells in Bone and Articular Cartilage Tissue Regeneration

Abstract

Multiple factors including trauma, infection, ageing, obesity and tumours result in bone and cartilage defects. The regeneration and functional restoration of bone and cartilage remains a significant clinical challenge. ‘Autologous grafts’ continue to remain the ‘gold standard’ in both bone and cartilage regeneration but stem cell-based therapies offer great promise in both these areas. Despite the plethora of stem cells that exist within the human body, the challenge remains in identifying the most beneficial cell type, assessing their availability, expansion under cGMP culture conditions, differentiation potential and functional restoration capacity. Embryonic stem cells; mesenchymal stem cells from the bone marrow, synovial fluid, adipose tissue and umbilical cord; and primary articular chondrocytes are some of the candidate cell types that are extensively studied in the context of bone (and cartilage) regeneration. The limited regeneration potential of cartilage adds further complexity to cartilage tissue engineering compared to the bone. However, major bone reconstruction as in the case of large bone defects due to tumour resection, fractures, and skeletal deformities is equally challenging. Incorporation of novel biomaterials, understanding the optimal cell-scaffold interactions, the addition of growth factors and provision of molecular cues are all essential in achieving effective tissue regeneration. Intensive effects in tissue regeneration can actually predispose to tissue hypertrophy, which also limits functional capacity. The current state of-the-art in both bone and cartilage regeneration is reviewed in this chapter, which highlights the importance of combined approaches involving stem/progenitor cells, biomolecules and/or biomaterials for therapies as well as rehabilitation and improvement in quality of life.