Structural assessments in decellularized extracellular matrix of porcine semilunar heart valves: Evaluation of cell niches

Abstract

Tissue-engineered heart valves aim to reproduce the biological properties of natural valves with anatomically correct structure and physiological performance. The closest alternative to creating an ideal heart valve substitute is to use decellularized porcine heart valves, due to their anatomy and availability. However, the immunological barrier and the structural maintenance limit the long-term physiological performance of decellularized porcine heart valves. This study investigated the extracellular matrix (ECM) structure of aortic and pulmonary porcine valves decellularized by a low concentration sodium dodecyl sulfate (SDS)-based method in order to determine the ECM scaffold (ECMS) conditions related to remodeling potential. To assess the structures of the leaflets and conduits of the heart valves, ECM components and their organization were evaluated by histology, biochemical analysis (BC), scanning electron microscopy, multiphoton microscopy, tensile test, immunofluorescence labeling (IF), and Raman microspectroscopy used to draw a profile of the cell niches. Histology and multiphoton imaging of decellularized aortic and pulmonary leaflets and conduits revealed a collagen and elastin histoarchitecture with rearrangement, loosening fibers, and glycosaminoglycan depletion confirmed by biochemistry quantification.The potential cytotoxicity of SDS residues was eliminated after 10 wash cycles. The mechanical properties of the structure of the valve indicated a functional resistance of decellularized ECM. The IF demonstrated the presence of basement membrane, suggesting a potential structure for host cell attachment. The RM analysis showed evidence of molecular interactions, suggesting conservation of the chemical composition, particularly among the protein molecular structures. The structural analyses performed in the semilunar porcine heart valves demonstrate that decellularized ECMS has structural properties that support physiological performance and potential host tissue integration. In fact, decellularized leaflet scaffolds were prone to cell interaction after human adipose-derived stromal cell seeding and culturing. Further analysis of biocompatibility, particularly the ECM-cell interaction, can elucidate the remodeling process, in preserved decellularized heart valve scaffold.

Xenotransplantation literature update, May/June 2019

“…Heart valve diseases induce structural changes in native valves and surgical intervention is needed when changes are severe . Surgical intervention involves repairing or replacing the native valve .…”

“…Immunologic hurdles continue to be an obstacle for long‐term physiological performance and structural integrity; Roderjan, João Gabriel, et al studied the extracellular matrix (ECM) structure integrity of porcine semilunar aortic and pulmonary heart valves decellularized with low sodium dodecyl sulfate (SDS) concentration in review of appropriate ECM scaffold (ECMS) conditions for remodeling potential . This is important as ECM structure affects valve structure and physiology . They dissected hearts from healthy male and female slaughterhouse pigs, aged 180‐210 days, and obtained six valves which they divided into four groups; the native porcine aortic valve (NPAV), the native porcine pulmonary valve (NPPV), the decellularized porcine aortic valve (DPAV), and the decellularized porcine pulmonary valve (DPPV) …”

“…This is important as ECM structure affects valve structure and physiology . They dissected hearts from healthy male and female slaughterhouse pigs, aged 180‐210 days, and obtained six valves which they divided into four groups; the native porcine aortic valve (NPAV), the native porcine pulmonary valve (NPPV), the decellularized porcine aortic valve (DPAV), and the decellularized porcine pulmonary valve (DPPV) …”

“…Roderjan et al's review of the rearrangements of histoarchitecture revealed that structural preservation of decellularized ECMS by low concentration SDS allows them to maintain physiological performance and encourage host tissue integration . The mechanical properties of the decellularized structures were also conserved through this process . However, decellularization was not able to eliminate DNA or Gal residues which may have an immunologic impact .…”

“…In the previous issue of Xenotransplantation, Zhang et al made a comprehensive review of porcine hepatic xenotransplantation, Li et al asses the use of New World capuchin monkey as NHP models, Zhao et al evaluate xenoimplications of IL‐6, TNF‐alpha, and IL‐17 signaling, Wang et al explored porcine renal development through SIX1 and SIX4 gene knockout studies, and Masuhiro et al studied clinical grade neonatal porcine bone marrow‐derived mesenchymal stem cells (npBM‐MSCs). Additionally, Terlecki et al researched bovine pericardial xenografts, Roderjan et al studied porcine semilunar heart valves, and Grebenik et al looked deeper into xenopericardial biomeshes. MartínezAlarcón et al performed a social study, focusing on the clinical perspective of xenotransplantation.…”