Apart from partial or total joint replacement, no surgical procedure is currently available to treat large and deep cartilage defects associated with advanced diseases such as osteoarthritis. In this work, we developed a perfusion bioreactor system to engineer human cartilage grafts in a size with clinical relevance for unicompartmental resurfacing of human knee joints (50mm diameter x 3mm thick). Computational fluid dynamics models were developed to optimize the flow profile when designing the perfusion chamber. Using the developed system, human chondrocytes could be seeded throughout large 50mm diameter scaffolds with a uniform distribution. Following two weeks culture, tissues grown in the bioreactor were viable and homogeneously cartilaginous, with biomechanical properties approaching those of native cartilage. In contrast, tissues generated by conventional manual production procedures were highly inhomogeneous and contained large necrotic regions. The unprecedented engineering of human cartilage tissues in this large scale opens the practical perspective of grafting functional biological substitutes for the clinical treatment for extensive cartilage defects, possibly in combination with surgical or pharmacological therapies to support durability of the implant. Ongoing efforts are aimed at integrating the up-scaled bioreactor-based processes within a fully automated and closed manufacturing system for safe, standardized, and GMP compliant production of large-scale cartilage grafts.2

BackgroundThe pericardial tissue is commonly used to produce bio-prosthetic cardiac valves and patches in cardiac surgery. The procedures adopted to prepare this tissue consist in treatment with aldehydes, which do not prevent post-graft tissue calcification due to incomplete xeno-antigens removal. The adoption of fixative-free decellularization protocols has been therefore suggested to overcome this limitation. Although promising, the decellularized pericardium has not yet used in clinics, due to the absence of proofs indicating that the decellularization and cryopreservation procedures can effectively preserve the mechanical properties and the immunologic compatibility of the tissue.Principal FindingsThe aim of the present work was to validate a procedure to prepare decellularized/cryopreserved human pericardium which may be implemented into cardiovascular homograft tissue Banks. The method employed to decellularize the tissue completely removed the cells without affecting ECM structure; furthermore, uniaxial tensile loading tests revealed an equivalent resistance of the decellularized tissue to strain, before and after the cryopreservation, in comparison with the fresh tissue. Finally, immunological compatibility, showed a minimized host immune cells invasion and low levels of systemic inflammation, as assessed by tissue transplantation into immune-competent mice.ConclusionsOur results indicate, for the first time, that fixative-free decellularized pericardium from cadaveric tissue donors can be banked according to Tissue Repository-approved procedures without compromising its mechanical properties and immunological tolerance. This tissue can be therefore treated as a safe homograft for cardiac surgery.

Duchenne’s muscular dystrophy is an X-linked neuromuscular disease that manifests as muscle atrophy and cardiomyopathy in young boys. However, a considerable percentage of carrier females are often diagnosed with cardiomyopathy at an advanced stage. Existing therapy is not disease-specific and has limited effect, thus many patients and symptomatic carrier females prematurely die due to heart failure. Early detection is one of the major challenges that muscular dystrophy patients, carrier females, family members and, research and medical teams face in the complex course of dystrophic cardiomyopathy management. Despite the widespread adoption of advanced imaging modalities such as cardiac magnetic resonance, there is much scope for refining the diagnosis and treatment of dystrophic cardiomyopathy. This comprehensive review will focus on the pertinent clinical aspects of cardiac disease in muscular dystrophy while also providing a detailed consideration of the known and developing concepts in the pathophysiology of muscular dystrophy and forthcoming therapeutic options.

Cardiac cell function is substantially influenced by the nature and intensity of the mechanical loads the cells experience. Cardiac fibroblasts (CFs) are primarily involved in myocardial tissue remodeling: at the onset of specific pathological conditions, CFs activate, proliferate, differentiate, and critically alter the amount of myocardial extra-cellular matrix with important consequences for myocardial functioning. While cyclic mechanical strain has been shown to increase matrix synthesis of CFs in vitro, the role of mechanical cues in CFs proliferation is unclear. We here developed a multi-chamber cell straining microdevice for cell cultures under uniform, uniaxial cyclic strain. After careful characterization of the strain field, we extracted human heart-derived CFs and performed cyclic strain experiments. We subjected cells to 2% or 8% cyclic strain for 24 h or 72 h, using immunofluorescence to investigate markers of cell morphology, cell proliferation (Ki67, EdU, phospho-Histone-H3) and subcellular localization of the mechanotransduction-associated transcription factor YAP. Cell morphology was affected by cyclic strain in terms of cell area, cell and nuclear shape and cellular alignment. We additionally observed a strain intensity-dependent control of cell growth: a significant proliferation increase occurred at 2% cyclic strain, while time-dependent effects took place upon 8% cyclic strain. The YAP-dependent mechano-transduction pathway was similarly activated in both strain conditions. These results demonstrate a differential effect of cyclic strain intensity on human CFs proliferation control and provide insights into the YAP-dependent mechano-sensing machinery of human CFs.