Discipline: Biological Sciences
Subcategory: Biomedical Engineering
Coral A. Torres Sánchez - University of Puerto Rico at Mayaguez
Cardiac remodeling and scar formation is a universal response to a myocardial infarction leading to tissue dysfunction. Current post-infarct treatments have reduced mortality in patients but there is still no effective method supporting myocardial healing. One major limitation is the loss of tissue-resident macrophages (M2) which are key cells to promote remodeling of the tissue. To address this limitation, we propose to evaluate anisotropic substrates for supporting M2 polarization in situ. Anisotropic surfaces and cytokines have been shown to influence macrophage polarization state. We hypothesized that the use of an anisotropic collagen fibrous patch will enable and enhance M2 polarization. To test our hypothesis, we evaluated polarization of THP-1 and peripheral blood monocytes in electrospun substrates of various degrees of anisotropy. SEM images were analyzed to confirm degree of fiber in electropsun substrates composed of Polycaprolactone (PCL) or high purity collagen type I. Substrates with >80% oriented fibers were classified as aligned. Gelatin-based coating and tissue culture plastic were used as controls for no fibers and integrin activation. Double sided medical-grade tape, which is used to immobilize the membranes on culture surfaces, was also evaluated. Monocyte, Phorbol myristate acetate (PMA) treatment and cytokine cocktails were used as negatives and positive controls for M1 and M2 polarization. Gene expression levels of CCR7 and CD206/CD163 receptors were measured to confirm and distinguish among M1 or M2 polarization. M2 polarization in aligned collagen membranes showed over 100-fold increase for CD206 expression when compared with tissue culture plastic (p<0.01). Activation levels were greater for random collagen membranes, showing a >90-fold increase (p<0.0001). Expression of CD206 in gelatin-based coating decreased 100-fold when compared to tissue culture plastic (p<0.05). Moreover, spontaneous polarization to M2 phenotype was detected in aligned collagen membranes and at a lower magnitude in random fibrils. Gelatin-based coating did not support M2 polarization, indicating that the observed effects are not dependent on integrin-mediated cell adhesion to RGD binding sites present in collagen I fibers. These results demonstrate that anisotropic substrates promote and enhance polarization to M2 phenotype. The data obtained will be used to support the use of fibrous substrates for tissue remodeling and delivery of cardiomyocytes after a myocardial infarction. References: Domenech, M., Polo-Corrales, L., Ramirez-Vick, J. E. & Freytes, D. O. Tissue Engineering Strategies for Myocardial Regeneration: Acellular Versus Cellular Scaffolds? Tissue Eng. Part B Rev. 22, 438?458 (2016).
Funder Acknowledgement(s): The authors would like to acknowledge the NSF ERC CMaT EEC-1648035 for supporting these research studies.
Faculty Advisor: Maribella Domenech, PhD, email@example.com
Role: All experiments and data analysis were done by me.