“The authors have discerned critical methods for heart valve scaffold preservation that may fundamentally change the way that heart valve reconstruction is performed.”
In an article in peer- reviewed publication Tissue Engineering, researchers have established techniques by which the biological scaffold or “extracellular matrix” that gives structure to a heart valve, can be freeze-dried and stored for later use as a tissue-engineered replacement valve to treat a failing heart, as described in an article in Tissue Engineering, concluding that decellularised porcine pulmonary valves can be used to obtain viable and biomechanically stable constructs. The full paper can be found here.
For a biological material to act as a suitable scaffold to be used as a valve replacement it has to have certain characteristics, which have formed the target for the group undertaking this research work. It needs to be acellular, likely to mimic the functional performance of a healthy valve, permit appropriate tissue ingrowth and degrade in a controlled and predictable fashion.
According to the researchers “an engineered scaffold should possess cell attachment and signalling molecules that will promote cell population and function, resulting in remodelling of the scaffold into a tissue construct.”
Furthermore practical considerations demand that the material must be transportable and storable, making freeze-drying a potentially advantageous technique, although various protective measures need to be taken in processing to protect the histological architecture of the material. The impact of these lyoprotective measures is discussed below.
The research work
Shangping Wang and colleagues from Leibniz University, Corlife, and Hannover Medical School, Hannover, Germany, studied various strategies for freeze-drying porcine heart valves in order to optimise the material for its purpose. After the cellular material was removed, scaffolds were freeze-dried with or without sucrose and hydroxyl ethylene starch. Stability, elasticity, pore size and physical structure were then compared in order to assess the effectiveness of these lyoprotectants in preventing degradation of the scaffolds. The paper concludes that “biomechanical tests show that decellularisation significantly affects the biomechanical properties of the tissue. Interestingly, the biomechanical properties of the valves freeze-dried with sucrose more closely resemble those of native tissue than the decellularized tissue.”
“Advances in heart valve technology are essential for improvement of patient care,” says John Jansen, DDS, PhD, Methods Co-Editor-in-Chief and Professor and Chairman, Department of Biomaterials, Radboud University Nijmegen Medical Center, The Netherlands. “The authors have discerned critical methods for heart valve scaffold preservation that may fundamentally change the way that heart valve reconstruction is performed.”
Source: Tissue Engineering, Part C: Methods, a peer-reviewed journal from Mary Ann Liebert, Inc.