Introduction Cardiovascular disease is the leading cause of mortality in the United States. Over half of these patients die from coronary artery disease. This study uses novel bioengineering methods toward the development of functional, biocompatible small-diameter arteries grown in vitro for use as bypass grafts in treating coronary artery disease.
Methods The scaffold for the artificial artery was made by electrospinning collagen (50 mg/mL) and elastin (25 mg/mL) dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFP). Gluteraldehyde was added to the solution to mediate fiber cross-linking. Human adipose stem cells (hASCs) were isolated from lipoaspirate samples and subjected to various differentiation protocols to produce smooth muscle cells (SMCs) and endothelial cells (ECs), the two cellular components of native arteries. The electrospun scaffold was seeded with hASCs to determine cell viability.
Results Scanning electron micrographs (SEMs) showed electrospun fibers. Mechanical testing of the sheet of fibers showed a tensile strength of 6.23 MPa. Immunofluorescence staining demonstrated that hASCs were positive for SMC markers: SM-α-actin, h-caldesmon, calponin, and SM-myosin. At confluence, hASCs formed a network of branched tube-like structures and were positive for EC markers: CD31, CD144, and vWF. SEMs showed that hASCs populated the electrospun scaffold, produced their own extracellular matrix, and migrated into the fiber structures.
Conclusion and Future Directions This work has shown that the electrospun collagen and elastin can be used as a durable scaffold, the hASCs can differentiate into SMCs and ECs, and the hASCs can attach to and proliferate within the electrospun scaffold. Future studies will consist of purifying the SMC and EC population from the hASCs, seeding the purified SMCs on a tubular electrospun scaffold under pulsatile flow conditions for 4 to 6 weeks, seeding the purified ECs on the luminal side of the tubular electrospun scaffold for 3 to 7 days under the same conditions, testing the mechanical properties of this cellular construct, and performing in vivo studies by implanting and immunostaining the construct to determine functionality and biocompatibility.
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