Intact microglia are cultured and non-invasively harvested without pathological activation using a novel cultured cell recovery method

Because spontaneous host regeneration of damaged tissues is limited, novel therapeutics utilizing cultured cells with the aid of tissue engineering me thods are promising alternatives for tissue replacement. One critical short coming is current requirement for invasive cell harvest from culture to fab ricate cell-based devices. Although microglia that secrete neurotrophic fac tors are attractive candidates for novel cell transplantation therapy for d amaged central nervous system tissue, the intact harvest of cultured microg lia is presently not achievable, Therefore, primary microglia were plated o nto culture surfaces grafted with the temperature-responsive polymer, poly( N-isopropylacrylamide) (PIPAAm). This surface undergoes rapid, reversible t emperature-dependent changes in its hydration state and surface hydrophilic ity. Microglia attached and proliferated on PIPAAm-grafted dishes at 37 deg reesC. By reducing culture temperature, more than 90% of the cells spontane ously detached from the dishes within several minutes without trypsin or ED TA treatment. Recovered and replated microglia exhibited phenotypic propert ies comparable to those of primary microglia freshly isolated From brain. B y contrast, less than 60% of the cells were harvested by trypsin digestion, and exhibited significant alteration of characteristic cellular properties as monitored by pathological states in vivo. This new technology exhibits utility for the preparation of cell sources required fur cell transplantati on as well as microglial function analysis. (C) 2001 Elsevier Science Ltd. All rights reserved.