Altered growth and attachment of rabbit crypt colonocytes isolated from different developmental stages.

The rabbit colon was used to establish an in vitro model for examining development-related cellular changes in colonocyte function. Colonic epithelia from newborn, weanling, and adult animals were separated from the muscle and subjected to enzymatic digestion. A mixture of 0.05% Pronase, 0.015% collagenase IV, and 0.023% DTT was determined to be optimal for the isolation of newborn and weanling colonocytes. This solution yielded significantly more cells and of greater viability than a 0.1% Pronase, 0.03% collagenase IV, 0.07% DTT mixture that is optimal for adult colonocytes. The epithelial origin of the colonocytes was confirmed by immunofluorescent staining of cytokeratins. The isolation procedure resulted in a crypt-enriched population and the cell yield/g of mucosa increased with age as did the crypt depth. Colonocyte viability of adults but not of newborns and weanlings, declined from 24 to 72 h. When grown on plastic, the newborn and weanling colonocytes show a approximately 2-fold increase in number, DNA and protein content over 48 h. In contrast, for all three parameters the adult colonocytes revealed only a approximately 10% increase. The colonocytes also showed an age-related decline in attachment to extracellular matrices. Colonocytes showed maximal attachment to Matrigel and collagen IV; newborn and weanling colonocytes show > 80% attachment, whereas adult colonocytes showed only a 45% attachment. The efficacy of attachment to Matrigel compared with that on plastic also differed with age, representing 9.3-, 5.5-, and 4.4-fold increase in adult, weanling, and newborn colonocytes, respectively. Newborn and weanling colonocytes grown on Matrigel for 48 h, showed a significant, 15% increase in cell number, DNA, and protein content compared with those grown on plastic. There was no difference in these parameters when adult colonocytes grown on Matrigel were compared with those grown on plastic. In summary, we have established an in vitro model for studying colonic epithelial cells at different stages of development.