Short-term and low-level priming of TLR4 (left side) and TLR3 (right side) leads to the polarization of heterogeneous BMSC preparations into a pro-inflammatory MSC1 phenotype or an immunosuppressive MSC2 phenotype . The proposed agonists for the toll-like receptor (TLR) priming schemes are listed in the yellow boxes above the specific priming scheme. We speculate that MSC1 may contribute to early tissue injury responses while MSC2 may contribute to later tissue resolution responses based on similar contributions by polarized monocytes in wound healing [83–85]. Poly(I:C), polyinosinic:polycytidylic acid. Figure adapted from .