Hydrogel Biomaterials for Stem Cell Microencapsulation

Abstract

Stem cell transplantation has been recognized as a promising strategy to induce the regeneration of injured and diseased tissues and sustain therapeutic molecules for prolonged periods in vivo. However, stem cell-based therapy is often ineffective due to low survival, poor engraftment, and a lack of site-specificity. Hydrogels can offer several advantages as cell delivery vehicles, including cell stabilization and the provision of tissue-like environments with specific cellular signals; however, the administration of bulk hydrogels is still not appropriate to obtain safe and effective outcomes. Hence, stem cell encapsulation in uniform micro-sized hydrogels and their transplantation in vivo have recently garnered great attention for minimally invasive administration and the enhancement of therapeutic activities of the transplanted stem cells. Several important methods for stem cell microencapsulation are described in this review. In addition, various natural and synthetic polymers, which have been employed for the microencapsulation of stem cells, are reviewed in this article.

Keywords: hydrogel; microencapsulation; stem cell; tissue engineering.

Figure 1

A schematic of the microencapsulation of stem cells and benefits in therapeutic applications.

Figure 2

Common polymers used for hydrogels and cell delivery.

Figure 3

Electrospraying for microbeads production and stem cell encapsulation. Illustration of a typical electrospraying process (a) and a vibration nozzle-equipped system (b).

Figure 4

Microfluidic-based microdroplet generation by T-junction, flow focusing, and co-flowing methods.

Figure 5

Schematic illustration of (A) photolithography and (B) micro-molding methods for cell encapsulation in microgels.

Figure 6

Stem cell encapsulation by an emulsion method.