Associate Professor Wayne State University Detroit, Michigan, United States
Introduction: Chronic kidney disease (CKD) is growing at a very rapid rate in the U.S. with 35.5 million Americans currently affected. End stage renal disease (ESRD) is the final stage of the disease’s progression, where the only methods of treatment are limited to kidney transplants and dialysis. Dialysis necessitates implementation of an access point into the patient, with the gold standard being an AV fistula in the patient’s forearm. AV fistulas possess multiple shortcomings such as needing to rotate needle insertion sites for improved healing, long-term failure arising from continuous high pressure arterial flow, and needing up to 12 weeks for full maturation to be a viable access point. Current alternative access points, namely synthetic grafts, do not possess adequate wound healing characteristics in comparison to those of AV fistulas; the ability to harness the body’s regenerative qualities is what sets AV fistulas apart from other methods. Here, we present findings on the ability of a biological engineered blood vessel (BEBV), to close puncture wounds inflicted on it, assessing its potential for utilization as a long-term access point. Possessing the capabilities to close puncture wounds repeatedly, and in time before needing to puncture the same location, is the benchmark tested for in this preliminary assessment of the BEBVs’ wound closure abilities.
Materials and
Methods: The wound healing capabilities of our cells were preliminarily determined with a scratch assay on plates of human patient derived dermal fibroblasts (pt-fibs). These cells are harvested from tissue received from plastic surgery interventions and obtained with patient consent per the approved protocol per Wayne State University’s Institutional Review Board. Four plates were uniformly scratched on the cell surface of the plates. Two pt-fibs plates had no growth factor, and the other two had PDGF at 10ng/mL to study its effect since PDGF is expressed by fibroblasts in the body. The plates were imaged every 24 hours for 4 days while in culture and wound closure was quantified using ImageJ. The BEBVs were constructed using pt-fibs following our laboratory’s protocol of stacking vascular tissue rings vertically to form cylindrical vessels. The vascular tissue rings were made by seeding pt-fibs into a 35mm plate with a central post. The cell monolayer formed and detached from the bottom of the plate, aggregating around the post forming a ring. These pt-fib rings were stacked into a vessel and cultured for at least one month. A vessel holding device was designed, allowing for the vessels to be punctured and imaged by a microscope while in culture. The vessels were punctured and imaged at 24-hour intervals for a week. To determine the wound closure capabilities of the vessels, ImageJ was used to calculate the change in the puncture wound’s size and histological stains of H&E were conducted at the end of the 7-day period.
Results, Conclusions, and Discussions: The plates of fibroblasts with PDGF in their medium that were scratched healed at a faster rate than those without growth factor and the BEBVs’ wound sites closed a statistically significant amount. Histology revealed that some cells infiltrated and proliferated in the part of the vessel that was punctured. This highlights that the BEBVs can close puncture wounds inflicted. The efficacy of the BEBV as an access point possesses advantages over synthetic grafts in that it utilizes patient derived cells with the ability to close puncture wounds in the short-term, and potentially the long-term. This success allows for further investigation into the BEBVs ability to close wounds when introducing other variables such as blood flow. This research also creates the foundation upon which further investigations into optimization of other parameters such as vessel diameter and their effects on the wound closure of the BEBVs can be conducted. Further development of this BEBV will yield a novel long-term access point that harnesses the body’s regenerative abilities.
