Design of a 3D‐bioprinted mesenchymal stem‐cell laden construct for accelerating angiogenesis in diabetic wounds

Diabetic wounds are a major complication of diabetes that can be debilitating to patients, with approximately 29.1 million people living with diabetes in the United States. A major contributor to delayed and/or inadequate healing of diabetic wounds is aberrant angiogenesis and vascularization. This study focused on the development and validation of an adult mesenchymal stem cell‐laden, hybridized chitosan (CS) and polycaprolactone (PCL) scaffold for accelerating angiogenesis in a diabetic wound. We preliminarily used an established murine cornea wound model in hyperglycemic, heterozygous Ins2(Akita) mice to test wound in a diabetic mammal. We applied silver nitrate to induce a chemical burn on the surface of the cornea ( Figure 1A). Then, we conducted non‐invasive, intravital imaging of vascularization into the wound bed over time. We observed neovessels in this diabetic wound model were decreased in number, consistent with the presence of abundant subconjuctival hemorrhages in diabetic corneas as seen in Figure 1B. After three and seven days post‐injury, there was a 1.05 and 1.09‐fold reduction in wound size for healthy models and 1.02 and 1.05‐fold reduction for diabetic models. This information was crucial in the formal scaffold size optimization, particularly with the coverage of the silver nitrate burn site. We confirmed that the two polymer solutions are able to copolymerize to form a biomaterial that would promote cell viability and exhibits biodegradation, based on previous research in CS‐PCL material properties ( Figure 1C). As the eye is 2.0 mm in diameter and burn size is approximately 0.5 mm in diameter, a scaffold of approximately 1 mm with 0.1 mm 2 pores was seeded with human adipose‐derived mesenchymal stem cells to allow for migration of cells with an approximate diameter of 22 μm into the wound site. By using a scaffold of 1 mm, stem cells are in close proximity to the angiogenic vessels, and cover the entire wound area. In order to ensure reproducibility in our scaffold fabrication, we used a state‐of‐the‐art 3D‐bioprinter to print the CS‐PCL co‐polymer into a contact lens architecture for the mouse eye. This model of angiogenesis in the diabetic mouse can be leveraged to evaluate biomanufactured tissue constructs, including cell‐seeded, 3D‐bioprinted implants to accelerate wound healing in diabetic patients. The creation of this construct will enable future implementation in other wound‐healing models of angiogenesis, such as in diabetic ulcers and thermal‐burn injury. Support or Funding Information Grant Funding Support: American Physiological Society Undergraduate Research Excellence Fellowship and University of Virginia Alumni Association Jefferson Trust Grant 1Experimental design. (A) Animal modeling of vessel growth due to corneal burn injury to the center of the cornea; (B) Comparison of healthy and diabetic angiogenesis during wound recovery; (C) Optimization of the appropriate CS‐PCL biomaterial; (D) Bioprinting in action on the RegenHU device; (E) Sample “honeycomb” pattern pictured during the completion of one layer of a sample scaffold.