Figure 1. Effects of MSC Injection on Allergen-Induced AHR and Inflammation.

C57Bl/6 mice (n=8 per group) were sensitized to OVA and then exposed to aerosol challenge with OVA, as described in Methods. In (A), the effects of a single i.v. injection of 2x10⁵ adipose-derived MSC immediately prior to first aerosolized OVA challenge on AHR were assessed in allergen sensitized mice (OVA MSC/OVA) and compared to AHR in OVA sensitized mice injected with PBS (OVA PBS/OVA) and to AHR in sham sensitized mice (PBS/OVA). In some group of mice, MSC or PBS was injected following allergen challenge in sensitized mice (OVA/OVA MSC and OVA/OVA PBS respectively). Injection of MSC prior to or following allergen challenge significantly reduced AHR in OVA sensitized and challenged mice (*p<0.05 versus OVA/OVA+PBS and +p<0.05 versus PBS/OVA). In (B), effects of MSC injection on numbers of eosinophils in BAL fluids were assessed. Mice injected with MSC had significantly fewer eosinophils in their airways than PBS-injected mice (*p<0.05). In (C), representative photomicrographs of cellular responses in the lung tissue sections of sham-sensitized but OVA challenged mice (a and f), OVA sensitized and challenged mice received vehicle (b and g) or MSC injection (c and h) prior to OVA challenge, and vehicle (d and i) or MSC injection (e and j) following the last OVA challenge were assessed using routine histology. Panels a, b, c, d and e: H&E staining; panels f, g, h, i, and j: PAS staining. In (D), PAS+ areas were quantified and analyzed. PAS+ areas were significantly decreased in mice that received MSC (n=5 per group) (*p<0.05). In (E), effects of MSC injection on BAL concentrations of IL-4, IL-5, and IL-13 were assessed. Concentrations of IL-4, IL-5, and IL-13 were significantly decreased in MSC-treated mice compared to untreated sensitized mice. Conversely, concentrations of IL-10- were significantly increased (*p<0.05).