Areas of Research

Cardiovascular diseases are the number one cause of death worldwide, taking about 18 million lives each year. Our research laboratory focuses on establishing novel cellular, tissue engineered, and animal models of human cardiovascular diseases for the purpose of elucidating causative mechanisms and identifying therapeutic interventions to treat these diseases.

Vascular Tissue Engineering and Repair

Our group has used Sendai virus, integration-free technology to produce induced pluripotent stem cells (iPSCs) from somatic human donor cells via introduction of stem cell factors. iPSCs are self-renewable and can differentiate into functional vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), providing an unlimited source of vascular cells for generation of tissue-engineered vascular grafts (TEVGs) for treating narrowing/blockage of arteries?the largest cause of mortality in the developed world.

Figure 1. Strategies for Generating hiPSC-TEVGs for Treating Vascular Injuries.

We have generated mechanically robust small-diameter (2-4 mm) TEVGs by seeding human iPSC-VSMCs onto biodegradable polyglycolic acid (PGA) scaffolds in custom made bioreactors. Coupled with decellularization and subsequent re-endothelialization strategies using human iPSC-derived ECs (hiPSC-ECs) in both rat and pig models (Fig. 1A), our studies lay the foundation for the future production of therapeutic, “off the shelf” ready TEVGs for clinical use. Additionally, we are developing culture strategies to create fully cellular “universal” endothelialized hiPSC-TEVGs (Fig. 1B) that are immunocompatible and readily available to any patient recipient. Recent studies were reported in Gui et al., Biomaterials 2016, 102:120-129; Luo et al., Cell Stem Cell 2020, 26:251-261; and Luo et al., Circulation Research 2022, 130:925-927 in collaboration with Dr. Laura Niklason. New scientists are welcome to join and learn stem cell biology, tissue engineering, and animal modeling.

Figure 2. Schematic of Universal hiPSC-TEVG.

We have developed “universal” human iPSCs by using CRISPR-Cas9 technology to knock-out the adaptive immune mediating MHC class I and II molecules, paired with the ectopic expression of the macrophage and natural killer (NK) cell suppressor molecule CD47 with TALEN-mediated insertion at the AAVSI "safe harbor" gene locus (Fig. 2A). We utilize RRGS rats, which are deficient in T, B, and NK cells and allow effective immune humanization with human peripheral blood mononuclear cells (PBMCs) (Fig. 2B), to assess the immunogenicity of engineered tissues using this “universal donor” cell line. Immune-humanized rats enable the investigation of the efficacy of decellularized hiPSC-TEVGs endothelialized with universal hiPSC-ECs (Fig. 2C), establishing the foundation for future assessments of this TEVG system in non-human primates as a therapeutic. New scientists can join this project and learn CRISPR and TALEN gene editing, tissue engineering, and immunology.