A novel, cost-effective approach to cell-cultured milk production: Progesterone and MMP inhibition promote lactogenic differentiation in bovine mammary epithelial cells

Recent advances in cellular agriculture have enabled the synthesis of cell-cultured milk components through hormonal regulation in bovine mammary epithelial cells (BMECs). Progesterone (PG) promotes proliferation and alveolar structure formation, whereas prolactin (PRL) induces milk secretory differentiation. However, the high-priced PRL remains a major limitation for cell-cultured milk production. Therefore, our study aimed to find a cost-effective alternative to PRL by identifying the mechanistic differences between proliferation and differentiation in BMECs. This insight enabled testing whether combining PG and an MMP-2/9 inhibitor could induce milk component production. The data demonstrated that a key mechanistic difference exists between PRL and PG regarding their regulation of MMP-2/9 activity. Combining PG with an MMP-2/9 inhibitor effectively promoted milk component production at levels comparable to PRL. These findings highlight the potential for cost-effective PG to replace expensive PRL for inducing lactogenic differentiation, offering the way for more affordable and commercially viable cell-cultured milk production. • Progesterone (PG) upregulated key markers of milk secretory differentiation. • PG enhanced MMP-2/9 activity, leading to degradation of claudin-3 and laminin. • PG and MMP-2/9 inhibitor increased milk component production in 3D-cultured cells. • PG and MMP-2/9 inhibitor are a cost-effective substitute for high-priced prolactin. • More affordable cell-cultured milk requires further technological advancements.