Superiority of three-dimensional stem cell clusters over monolayer culture: An archetype to biological application

Mesenchymal stem cells (MSCs) are attractive and potential alternatives to cell-based therapeutics in the field of regenerative medicine. Various clinical trials are being conducted to investigate the therapeutic efficacy of MSCs in a variety of diseases. Many studies show three-dimensional (3D) aggregates as more physiologically relevant than conventional two-dimensional (2D) cultures. Cell morphology, viability, functionality, as well as various gene expressions at the molecular level are drastically changed after 3D culture. MSCs as 3D aggregates provide enhanced differentiation potential and upregulation of pluripotency markers that subsequently result in stemness of MSCs. Furthermore, other biological properties like angiogenic effect, anti-inflammatory effect, regenerative effect, and survival after transplantation are also significantly enhanced in spheroids. Thus, 3D culture is a novel approach in cell-based therapeutics applicable in the field of regenerative medicine and tissue engineering, immunomodulatory diseases and organ transplantation for improved therapeutic outcomes. Various mechanism and techniques have been described for the formation of spheroids in different studies, some of which are discussed here. However, the molecular mechanism underlying the improved functionality and other changes is still unclear and requires further research. Similarly, clinically relevant studies are required to establish the clinical applicability.