Human AB serum and thrombin-activated platelet-rich plasma are suitable alternatives to fetal calf serum for the expansion of mesenchymal stem cells from adipose tissue

MSCs are currently in focus regarding their clinical potential in cell therapy and tissue engineering. However, most isolation and expansion protocols for clinical-scale production of MSCs use fetal calf serum (FCS) as a supplement, which poses a potential risk for infections as well as immunological reactions. To find a suitable FCS substitute, we investigated the effects of pooled human AB serum (AB-HS) and thrombin-activated platelet-rich plasma (tPRP) on adipose tissue MSCs (AT-MSCs) with FCS as the standard control medium. AT-MSCs of 10 donors were cultured under three different conditions: (a) 10% FCS, (b) 10% ABHS, and (c) 10% tPRP. Colony-forming units, cumulative population doubling rates, and differentiation capacity toward the adipogenic and osteogenic lineages were assessed, along with immunophenotype. We demonstrated that AB-HS and tPRP provide a significantly higher proliferative effect on AT-MSCs than does FCS. In the first six passages, AB-HS and tPRP MSCs exhibited a fold expansion of 66.6 +/- 15.7 and 68.1 +/- 6.7, respectively, compared with 24.4 +/- 0.7 for FCS. Differentiation capacity was preserved throughout long-term culture. Immunophenotype was characteristic for MSCs and comparable for all culture conditions with the exception of a distinct CD45-/CD14-positive side population for AB-HS and tPRP that tended to diminish with prolonged culture. We showed that pooled human AB serum and thrombin-activated platelet-rich plasma are alternatives to FCS for AT-MSCs. These human sources are better characterized regarding potential infectious threats, while providing a higher proliferation rate and retaining differentiation capacity and mesenchymal stem cell marker expression throughout long-term culture.