Primary culture of porcine mammary epithelial cells as a model system for evaluation of milk protein expression.

Porcine mammary epithelial cells were isolated to culture on collagen gel followed by gel floating treatment to evaluate differentiation under the culture conditions of serum-free medium, supplemented with combinations of insulin, hydrocortisone, and prolactin. After the culture period, the mammary cells attached to the collagen gels were recovered to observe expression of beta-casein, beta-lactoglobulin, and lactoferrin by reverse transcriptase polymeric chain reaction method. Expression of beta-casein was observed in the presence of insulin, hydrocortisone, and prolactin whereas transcription of beta-lactoglobulin and lactoferrin occured irrespective of hydrocortisone and prolactin. Immunoblot analysis demonstrated synthesis and secretion of lactoferrin in the fraction of recovered cells and the culture medium.