Background
Aortic valve prosthesis recipients must choose between two undesirable options: mechanical and tissue prostheses, each with certain advantages and disadvantages. In addition, prostheses cost upwards of $25,000, making them inaccessible for many. The shortcomings of both categories mean that developing an aortic valve prosthesis that is durable and biocompatible is critical. DLP bioprinting is the ideal vehicle for creating biocompatible, tissue-like constructs, and thus for this study.
Methods
Due to lack of access, a commercial-grade DLP printer was modified for bioprinting. The prosthesis was designed with three leaflets, each ~1 mm thick, mimicking the natural human aortic valve. Durability, hemodynamics, and mechanical characteristics were used as metrics for valve performance. A mock circulatory loop (MCL) capable of testing for 12 consecutive hours was developed, allowing for durability assessment. Using various software, a simulated patient was created, characterized by cardiovascular health indicators.
Results
The tested prosthesis had virtually no stenotic characteristics, with flow resistance ~1.01% (12-hour average). Backflow was marginally higher, at ~5.69% (12-hour average). This led to a highly stable systolic pressure. Diastolic pressure fluctuated slightly more, but still remained within acceptable values; cardiac output remained near ~4.3 l/min. In addition to decent mechanical performance, hemodynamics was extremely favorable. The simulated patient had a hemolysis rate of ~1.53%. One of the most remarkable aspects of the prosthesis is that its performance improved over time, as did the patient's condition.
Conclusions
This study has demonstrated the feasibility of DLP bioprinting aortic valve prostheses which have favorable characteristics and could be a potential alternative to current prosthetic valves. In addition, the fabrication of the valves was done cost-effectively, without the need for expensive equipment. Although the results are promising, many improvements could be made, especially in terms of testing protocols and mechanical characteristics of the prosthesis.