Reversible mitotic and metabolic inhibition following the encapsulation of fibroblasts in alginate hydrogels

Limiting cell proliferation without reducing cell viability for in vivo tissue engineering applications is important in co-culture applications where the growth of one cell type must be inhibited to prevent overgrowth of the scaffold at the expense of another cell type. Also, it is vital for maintaining viability of cells in large constructs before vascularisation occurs. In this study we have shown by means of the Thiazolyl blue (MTT) assay and immuno-staining for proliferating cell nuclear antigen (PCNA) that encapsulating fibroblasts in 2% and 5% w/v calcium-alginate at a density of 7.5 × 105 cells/ml as uniformly dispersed entities, enabled cells to maintain viability and caused a reversible mitotic inhibition. Alginate encapsulation also caused reversible metabolic inhibition as demonstrated by the MTT assay and fluorescent staining for mitochondrial membrane potential. Histological evaluation of the alginate constructs containing fibroblasts showed that mitotic and metabolic inhibition was possibly due to cell isolation during the first five weeks of culture. The alginate scaffold degraded with time releasing encapsulated fibroblasts. Upon implantation to a wound site this should ensure that encapsulated cells are able to replace the damaged tissue after sufficient proliferation of the co-cultured cell type or sufficient vascularisation of the construct.