Population Kinetics and Protein Profiles of Co-Cultured Adult and Fetus Rabbit Bladder Smooth Muscle Cells

Bladder tissue models have been developed using smooth muscle cells (SMCs) on various scaffolds to mimic bladder morphology and physiology. This study investigates the effects of co-culturing fetal and adult SMCs on growth properties and protein profiles to understand cellular interactions and population kinetics.

Bladder tissue samples from 10 adult and 10 fetal New Zealand rabbits were divided into 5 groups: adult SMCs (A), fetal SMCs (F), 50%A+50%F (A+F), 75%A+25%F (3A+F), and 25%A+75%F (A+3F). Population doubling time (PDT) of 3 × 106 cells from each group was measured after 48 and 72 hours. Protein concentrations were estimated by spectrophotometric analysis and analyzed via SDS-PAGE gel electrophoresis. Cells exhibited typical SMC morphology, confirmed by positive staining for α-SMA and MYH11.

Median cell counts of single cultures were significantly higher than co-cultures (P < .05), but cell viability was comparable (P > .05). Population doubling time at 72 hours for A, F, A+F, 3A+F, and A+3F were 89.4, 92.0, 89.4, 127.9, and 145.0 hours, respectively. Protein concentrations were similar between fetal and adult co-cultures (P > .05). Electrophoresis at 48 hours revealed a unique 80kDa band in adult cells and a 32kDa band in co-cultured cells.

Co-culturing resulted in increased PDT, altered protein concentrations, and changes in protein profiles, while each cell population maintained its phenotype. Fetal bladder SMCs maintained their morphology and viability when co-cultured with adult SMCs, resulting in a significant limitation in the cumulative proliferation rate. This may be dependent on alterations of protein profiles of adult and fetal SMCs promoted by rearrangements in co-cultures.