A Bioreactor with Compliance Monitoring for Heart Valve Grafts

Abstract

The drawbacks of state-of-the-art heart valve prostheses lead researchers to explore the prospect of using tissue-engineered constructs as possible valve substitutes. It is widely accepted that the mechanical properties of the construct are improved with mechanical stimulation during in vitro growth. We designed a new dynamic bioreactor with the perspective of using decellularized valve homografts as scaffolds in order to produce tissue-engineered valve substitutes. The design guidelines were (a) compatibility with the procedures for the treatment of homografts; (b) delivery of finely controlled pulsatile pressure loads, which induce strain stimuli that may drive cells toward repopulation of and integration with the natural scaffold; and (c) monitoring the construct's biomechanical status through a comprehensive index, i.e., its compliance. The handling needs during the set-up of the homograft and the use of the bioreactor were minimized. The bioreactor and its automated control system underwent tests with a compliant phantom valve. The estimated compliances are in good agreement with the measured ones. Tests were also carried out with porcine aortic samples in order to assess the hydrodynamic and biomechanical reliability. In the future, monitoring the construct's compliance might represent a key factor in controlling the recellularization of the valve homografts, which provides awareness of the construct's biomechanical status by real-time, non-destructive, and non-invasive means.

A Pulsatile Bioreactor for Conditioning of Tissue-Engineered Cardiovascular Constructs under Endoscopic Visualization

“…However, these bioreactors have major drawbacks. All these systems have a bulky design [20] and work with a lot of tubes [13,21] and screws [3]. In contrast, the bioreactor presented in this study has a compact and clearly arranged design and avoids the use of screws in the sterilized parts for an easy assembly of the bioreactor.…”

“…Another important difference between this bioreactor and the reactors found in literature [20] is that this bioreactor is not only designed for the actual conditioning process. This bioreactor was designed to be an intermediate step between the seeding and evaluation procedures.…”

In vitro hemodynamics and valve imaging in passive beating hearts

“…The resistances and the inertances were determined according to classical hydraulic laws (Pennati et al, 2004;Idelchik, 2008), which are reported in the additional material. The values of both the aortic root compliance (C ao ) and the systemic impedance simulator components (R cs , R cp , C cp , L cs ) were taken from the literature (Lanzarone et al, 2009;Vismara et al, 2009).…”

Cells, scaffolds and bioreactors for tissue-engineered heart valves: a journey from basic concepts to contemporary developmental innovations☆

“…In 2009, Vismara and colleagues [102] developed a prototype especially aimed at the production of viable grafts from decellularized human cadaveric valves. The instrument provided a diastolic pulse stimulation (DPS), obtained by applying transvalvular pressurization, while keeping the homograft in its closed configuration [103].…”