Lipocalin 24p3 Induction in Colitis Adversely Affects Inflammation and Contributes to Mortality.

Recognition of microorganism associated molecular patterns by epithelial cells elicits signaling cascades resulting in the production of host defense proteins. Lipocalin 24p3 is purported to be one such protein. 24p3 binds prokaryotic and eukaryotic siderophores and by sequestering iron laden bacterial siderophores it was believed to restrict bacterial replication. As such mice deficient for 24p3 are susceptible to systemic infections. However, it is not clear whether deficiency of 24p3 on the gut mucosa contributes to inflammation. In line with 24p3's function as a bacteriostat, it would be reasonable to assume that deficiencies in the control of intestinal flora from 24p3 absence play a role in inflammatory intestinal diseases. Surprisingly, we show 24p3 is a contributor of inflammation and 24p3 deficiency protects mice from dextran sodium sulfate (DSS)-induced colitis. 24p3 was found to be a negative regulator of platelet-derived growth factor (PDGF), which helps maintain the integrity of the gut mucosa. Neutralization of PDGF-BB abrogated resistance of 24p3 null mice to DSS confirming the direct link between 24p3 and PDGF-BB. Finally, iron handling in wild-type and 24p3-null mice upon DSS treatment also differed. In summary, differential iron levels and enhanced expression of PDGF-BB in 24p3 null mice confers resistance to DSS.

Characterization of Canine Adipose-Derived Mesenchymal Stromal/Stem Cells in Serum-Free Medium.

In this article, we report on the development of a defined serum-free medium capable of supporting the culture expansion of mesenchymal stromal/stem cells (MSCs) from canine adipose tissue (canine Ad-MSCs). The potential benefits of serum-free media can only be utilized if cells cultured in serum-free media maintain the same functional characteristics as cells cultured in serum-containing media. Therefore, we analyze the characteristics of canine Ad-MSCs cultured in this serum-free medium or in serum-containing medium through evaluation of growth kinetics, clonogenic capacity, senescence, and differentiation capacity. Both, serum-containing medium and our serum-free medium, supported efficient growth and colony formation of canine Ad-MSCs. In addition, canine Ad-MSCs cultured in both media demonstrated similar viability after freeze/thaw, similar cell surface marker expression, and were capable of trilineage differentiation. While canine Ad-MSCs cultured in both media were generally similar, under the conditions of our study, canine Ad-MSCs cultured in serum-free medium demonstrated a shorter lag phase and higher colony-forming capacity, accelerated population doubling, maintained multipotentiality at higher passage numbers, and underwent senescence at higher passage numbers compared to canine Ad-MSCs cultured in conventional serum-containing medium. These results suggest that canine Ad-MSCs cultured in serum-free medium retain the basic characteristics associated with canine Ad-MSCs cultured in serum-containing medium, although some differences in growth kinetics were observed.

Questions and Challenges in the Development of Mesenchymal Stromal/Stem Cell-Based Therapies in Veterinary Medicine.

The therapeutic potential of stem cells has fascinated those interested in treating diseases in both human and animal subjects. Although the exact mechanism of action and the definitive effectiveness of stem cell therapies remain unclear, animal owner perceptions and a desire for improved treatment options have fueled the interest of clinicians and stakeholders. Standards do not yet exist to define the critical attributes of mesenchymal stem/stromal cell (MSC)-based products derived from veterinary species such as the dog, cat, and horse. This has led veterinary stakeholders to adopt those guidelines and criteria set forth for human MSC-based products; however, these criteria are not always applicable to MSCs from dogs, cats, and horses (e.g., variability in species-specific cell surface marker expression and antibody cross reactivity). Establishing useful standards and meaningful product quality criteria as well as the understanding of full spectrum of MSC functions and preclinical evidence for safety and therapeutic efficacy for veterinary (companion and recreational animals) MSC-based-products will be critical to furthering product development, and may ultimately facilitate the availability of FDA-approved MSC-based products for use in veterinary medicine.