Modification of PLGA microspheres’ microstructure for application as cell carriers in modular tissue engineering

Microspheres (MS) made of resorbable polymer have been proposed as a cell growth support. They may be assembled to form cell constructs or be suspended in hydrogels allowing injection into injury location. High relative surface area of MS provides more efficient cell culture environment than traditional culture on flat substrates (multiwell plates, Petri dishes). In addition, MS structure, topography and surface chemistry can be modified to promote cell adhesion and proliferation. The aim of this study was to obtain resorbable poly(L-lactide-co-glycolide) (PLGA) MS and to modify their properties by changing manufacturing conditions of the oil-in-water emulsification to better control structural and microstructural properties of MS and their biological performance. To this end, water phase was modified by addition of NaCl to change ionic strength, while oil phase by addition of polyethylene glycol (PEG). Microstructural and thermal properties were assessed. Cytocompatibility tests and cell cultures with MG-63 cells were conducted to verify potential relevance of MS as cell carriers. The results showed that it is possible to obtain cytocompatible MS by oil-in-water emulsification method and to control diameter, porosity and crystallinity of MS with the use of additives to oil and/or water phases without negative changes in MS cytocompatibility. The results prove that modification of both phases make it possible to produce MS with desired/controllable properties like surface topography, porosity and crystallinity.