Building Stronger Endothelium in Microvessels with Platelet Rich Plasma

PRP perfusion improves 3D engineered vessel integrity and barrier function. Top panels: confocal image projection of engineered vessels after PRP (A) or enriched plasma (EnP) (B) perfusion overnight. Bottom panels: fluorescence images after 3 mins perfusion of 70kDa FITC-dextran through microvessels for both conditions.

Blood vessels are essential for human development and survival. Arteries, veins, capillaries and other types of vessels carry blood throughout the body, and with it, life-sustaining nutrients and oxygen required for the growth and repair of tissue, and for the maintenance of homeostasis. Blood vessel syndromes, like sepsis, or conditions associated with blood vessel functioning, like heart disease, can be deadly – and difficult to treat.

While researchers at the UW Institute for Stem Cell and Regenerative Medicine (ISCRM) and elsewhere are pioneering new methods of regenerating human tissue and modeling diseases, engineering effective vascular networks with mature vessel walls (endothelium) that effectively mimic native vasculature remains a critical challenge.

Now, a collaborative research effort led by ISCRM faculty member Ying Zheng, PhD, an Associate Professor in Bioengineering, has shown that perfusing engineered micro-vessels with another blood component, platelet‐rich plasma (PRP), produces stronger endothelium and significantly improves barrier function. The findings, published recently in the journal Advanced Science, point to new approaches to engineer implantable vascular networks.

Platelets are blood cells that are best known for their role in clotting and wound healing. Researchers have suspected for decades that PRP might also improve the functionality of engineered tissue. However, the degree to which PRP contributes to the integrity of the endothelium has been studied less extensively, in part because investigators lacked the 3D technology to explore the links between platelets and cell walls.

Ying Zheng PhD, Associate Professor of Bioengineering and ISCRM faculty member

In their research, Zheng and her team engineered 3D blood vessel systems to measure the effect of introducing PRP into a culture of blood cells. “In two dimensions, we wouldn’t see the effect at all,” explains Zheng.  “Vessels are three-dimensional tubes.  We need 3D capability to fully mimic pressure, flow, and other forces associated with vascularization.”

Using this 3D system, the ISCRM researchers were able to show that a perfusion of platelets contributed positively to the size and strength of the endothelium. The results suggest a broader role for platelets in blood vessel functioning and point to a promising new method for enhancing the effectiveness of engineered tissue. Improved tissue engineering methods, in turn, would have significant implications for 3D tissue printing, organoid technology, and other strategies for regeneration and disease modeling.

Contributors to this study include ISCRM faculty members Yuliang Wang,PhD, who provided bioinformatics analysis and Cole DeForest, PhD, whose lab – specifically, student Chris Arakawa – utilized photon microscopy expertise to injure endothelium. BloodworksNW researchers Jose Lopez and Junmei Chen also supported this research.

Acknowledgments:

R.J.N., J.A.L., and Y.Z. designed the project. R.J.N. and Y.Z. performed the experiments and analyzed the data with the assistance of R.M., C.A., C.D., J.C., and J.A.L. Y.W., L.W., and Y.Z. analyzed and interpreted RNA‐seq data. R.J.N. and Y.Z. wrote the manuscript. All authors edited and approved the manuscript. The authors acknowledge the Microfabrication facility and Lynn & Mike Garvey imaging core in the University of Washington, the Electron Microscope facility and RNA‐seq lab in Fred Hutchinson Cancer Research Institute. The authors thank Dr. Stephen Schwartz for helpful discussions. This project was supported by AHA 12SDG9230006 (to Y.Z.), NIH DP2DK102258 (to Y.Z.), R01HL141570 and UG3/UH3TR002158 (to Y.Z.), T32 training grant NIDDK0007467 (to R.J.N.), and K99/R00 DK114750 (to R.J.N.).