History, challenges and perspectives of cell microencapsulation

Abstract

Cell microencapsulation continues to hold significant promise for biotechnology and medicine. The controlled, and continuous, delivery of therapeutic products to the host by immunoisolated cells is a potentially cost-effective method to treat a wide range of diseases. Although there are several issues that need to be addressed, including capsule manufacture, properties and performance, in the past few years, a stepwise analysis on the essential obstacles and limitations has brought the whole technology closer to a realistic proposal for clinical application. This paper summarizes the current situation in the cell encapsulation field and discusses the main events that have occurred along the way.

Scaffolding in tissue engineering: general approaches and tissue-specific considerations

“…Cell encapsulation in self-assembled hydrogel matrix Encapsulation is a process entrapping living cells within the confines of a semi-permeable membrane or within a homogenous solid mass [66,86,87,113]. The biomaterials used for encapsulation are usually hydrogels, which are formed by covalent or ionic crosslinking of water-soluble polymers.…”

“…Many types of biomaterials including natural and synthetic hydrogels can be used for encapsulation provided that the conditions inducing the hydrogel formation or the polymerization are compatible with living cells. Encapsulation has been developed over several decades and the predominating use is for immunoisolation during allogenic or xenogenic cell transplantation [87,113]. Naturally occurring polysaccharides derived from algae, sodium alginate is the most commonly used material while other natural materials such as agarose [10] and chitosan [130] and synthetic materials such as poly (ethylene glycol) (PEG) [83] and polyvinylalcohol (PVA) [58] are also used.…”

Living Cell Factories ‐ Electrosprayed Microcapsules and Microcarriers for Minimally Invasive Delivery

“…By adjusting permeability, the capsule should still possess adequate mechanical stability, immune evasion and permit adequate exchange of nutrients and metabolic waste products [3] . Mass transfer across a membrane is governed by thermodynamic parameters that need to be tailored to the type and size of solutes, membrane thickness, etc.…”

“…The ability to create 'living cell factories' by combining hydrogels and cells can now facilitate cell transplantation in a permeable system while isolating the cells from the host's immune system has resurrected the concept of allogeneicbased therapies. Such approaches eliminate the need for immunosuppression in allogenic cell delivery or toxicity in host cell exposure to drugs and more targeted delivery mechanisms [3] .…”

Preservation of Embryonic Stem Cells

“…A major disadvantage of using small liquid droplets to confine cells is that the droplets will merge with each other unless they are dispersed in an oil phase, which makes it difficult to retrieve cells from the droplets. The hydrogel microcapsule (~250-1000 µm) of natural, biocompatible polymers such as alginate has been widely explored to confine or encapsulate a variety of living cells for transplantation and cell-based therapy (Chang 1996;Maguire et al 2006;Magyar et al 2001;Orive et al 2003;Orive et al 2004;Orive et al 2006;Rohani et al 2008;Torre et al 2007;Wang et al 2006a;Wang et al 2006b). Recently, living cells have been encapsulated in even smaller (~100 µm) microcapsules for better cell survival and transplanation effcacy ).…”