Keratinocyte differentiation can be induced by calcium in the culture media. As such, lowering the calcium concentration in a serum free media will greatly lower the chances keratinocytes terminally differentiating towards corneocytes. While Lonza offers most of our keratinocyte media in calcium free varieties, it is still required to add calcium. Without calcium, keratinocytes will not attach or proliferate. To retain good plating and survival of keratinocytes, Lonza suggests adding calcium to of any of our calcium free keratinocyte media at a final concentration of 0.03 mM (maybe even lower). Proliferation rates will be slower with lower calcium, however, the keratinocytes will be less subject to differentiation under these conditions.

Lonza’s standard KGM™ and KGM™-2 media both contain calcium at 0.15 mM.
Lonza’s standard KGM-Gold™ medium contains calcium at 0.10 mM.