Hector L. Osoria

Fabrication of capillary-like structures with Pluronic F127® and Kerria lacca resin (shellac) in biocompatible tissue-engineered constructs#

The fabrication of large cellular tissue‐engineered constructs is currently limited by an inability to manufacture internal vasculature that can be anastomosed to the host circulatory system. Creation of synthetic tissues with microvascular networks that adequately mimic the size and density of in vivo capillaries remains one of the foremost challenges within tissue engineering, as cells must reside within 200–300 μm of vasculature for long‐term survival. In our previous work, we used a sacrificial microfibre technique whereby Pluronic® F127 fibres were embedded and then sacrificed within a collagen matrix, leaving behind a patent channel, which was subsequently seeded with endothelial and smooth muscle cells, forming a neointima and neomedia. We now have extended our technique and describe two approaches to synthesize a biocompatible tissue‐engineered construct with macro‐inlet and ‐outlet vessels, bridged by a dense network of cellularized microvessels, recapitulating the hierarchical organization of an arteriole, venule and capillary bed, respectively. Copyright

A Novel Three-Dimensional Platform to Investigate Neoangiogenesis, Transendothelial Migration, and Metastasis of MDAMB-231 Breast Cancer Cells.

Background: A crucial step in the progression of cancer involves the transendothelial migration of tumor cells into the bloodstream and invasion at distant sites. Most in vitro models of malignant cell behavior do not account for the presence of and interaction with vascular cells. Three-dimensional platforms to further explore the factors responsible for metastatic cellular behavior are under intensive investigation. Methods: Hydrogels with encapsulated MDAMB-231 breast cancer cells were fabricated with a central microchannel. The microchannel was lined with a co-culture of human umbilical vein endothelial cells and human aortic smooth muscle cells. For comparison, co-culture–seeded microchannels without breast cancer cells (MDAMB-negative) were fabricated. Results: After 7 and 14 days, the endoluminal lining of encapsulated MDAMB-231 co-culture–seeded microchannels demonstrated aberrant endothelial cell and smooth muscle cell organization and breast cancer cell transendothelial migration. MDAMB-231 cells performed matrix remodeling, forming tumor aggregates within the bulk, migrating preferentially toward the hydrogel “neovessel.” In contrast, MDAMB-negative constructs demonstrated maintenance of an intact endoluminal lining composed of endothelial cells and smooth muscle cells that organized into discrete layers. Furthermore, the thicknesses of the endoluminal lining of MDAMB-negative constructs were significantly greater than encapsulated MDAMB-231 co-culture–seeded constructs after 7 and 14 days (p = 0.012 and p < 0.001, respectively). Conclusion: The authors have created a powerful tool that may have tremendous impact on furthering our understanding of cancer recurrence and metastasis, shedding light on these poorly understood phenomena.

Innovative 3D Collagen Microsphere Scaffold (MSS) Promotes Robust Cellular Invasion

METHODS: Utilizing Kepler’s conjecture of sphere packing, which states that the arrangement of spheres in a 3D space has a density of 74%, we fabricated 7 mm microsphere scaffolds (MSS) with a regular arrangement of density gradients. Type I collagen microspheres (1%, 0.6% or 0.4%), ranging 50 to 150 μm in diameter, were manufactured via an oil emulsion technique. MSS were fabricated by encasing microspheres of varying collagen density into collagen bulk of varying density (0.3%, 0.2% or 0.6%), so that 74% of the scaffold’s volume was comprised of microspheres and 26% of bulk collagen. MSS underwent thermal gelation at 37°C for 1 hour. Nonmicrosphere-containing 1% or 0.3% collagen scaffolds were fabricated as controls. Scaffolds were implanted subcutaneously in the dorsa of 8 week old wild-type mice and harvested for histological analysis after 7 or 14 days.