Microencapsulating and Banking Living Cells for Cell-Based Medicine

Abstract

A major challenge to the eventual success of the emerging cell-based medicine such as tissue engineering, regenerative medicine, and cell transplantation is the limited availability of the desired cell sources. This challenge can be addressed by cell microencapsulation to overcome the undesired immune response (i.e., to achieve immunoisolation) so that non-autologous cells can be used to treat human diseases, and by cell/tissue preservation to bank living cells for wide distribution to end users so that they are readily available when needed in the future. This review summarizes the status quo of research in both cell microencapsulation and banking the microencapsulated cells. It is concluded with a brief outlook of future research directions in this important field.

Figure 1

A schematic illustration of the concept of immunoisolation by encapsulating living cells in microcapsules that have a semipermeable wall to allow free diffusion of nutrients, metabolic wastes, and therapeutic agents while blocking any host immune mediators from getting in contact with the encapsulated cells.

Figure 2

Phase contrast (A and C) and fluorescence micrographs (B and D) of non-encapsulated (A and B) and encapsulated (C and D) cells after cryopreservation by vitrification. In the fluorescence micrographs (B and D), live and dead cells were stained green and red, respectively. The cell viability were high (> 95%) for both encapsulated and non-encapsulated cells before cryopreservation. Scale bars: 100 μm. Figure reprinted and redrawn from reference [134] with permission from Springer Publishing Co.

Figure 3

Fibrosis around encapsulated cells and broken microcapsules 2 days after transplantation, due to poor systemic biocompatibility and low mechanical stability/strength of microcapsules to encapsulate living cells. Figure reprinted and redrawn from reference [138] with permission from Elsevier.