Decellularized Extracellular Matrix Powder Accelerates Metabolic Maturation at Early Stages of Cardiac Differentiation in Human Induced Pluripotent Stem Cell-derived Cardiomyocytes

During fetal development, cardiomyocytes switch from glycolysis to oxidative metabolism to sustain the energy requirements of functional cells. State-of-the-art cardiac differentiation protocols yield phenotypically immature cardiomyocytes, and common methods to improve metabolic maturation require multistep protocols to induce maturation only after cardiac specification is completed. Here, we describe a maturation method using ventricle-derived decellularized extracellular matrix (dECM) that promoted early-stage metabolic maturation of cardiomyocytes differentiated from human induced pluripotent stem cells (hiPSCs). Chemically and architecturally preserved particles (45-500 µm) of pig ventricular dECM were added to hiPSCs at the start of differentiation. At the end of our maturation protocol (day 15 of cardiac differentiation), we observed an intimate interaction between cardiomyocytes and dECM particles without impairment of cardiac differentiation efficiency (~70% of cTNT+). Compared with control cells (those cultured without pig dECM), 15-day-old dECM-treated cardiomyocytes demonstrated increased expression of markers related to cardiac metabolic maturation, MAPK1, FOXO1, and FOXO3, and a switch from ITGA6 (the immature integrin isoform) to ITGA3 and ITGA7 (those present in adult cardiomyocytes). Electrical parameters and responsiveness to dobutamine also improved in pig ventricular dECM-treated cells. Extending the culture time to 30 days, we observed a switch from glucose to fatty acid metabolism, indicated by decreased glucose uptake and increased fatty acid consumption in cells cultured with dECM. Together, these data suggest that dECM contains endogenous cues that enable metabolic maturation of hiPSC-CMs at early stages of cardiac differentiation.

Modern Approaches to Acellular Therapy in Bone and Dental Regeneration

An approach called cell-free therapy has rapidly developed in regenerative medicine over the past decade. Understanding the molecular mechanisms and signaling pathways involved in the internal potential of tissue repair inspires the development of new strategies aimed at controlling and enhancing these processes during regeneration. The use of stem cell mobilization, or homing for regeneration based on endogenous healing mechanisms, prompted a new concept in regenerative medicine: endogenous regenerative medicine. The application of cell-free therapeutic agents leading to the recruitment/homing of endogenous stem cells has advantages in overcoming the limitations and risks associated with cell therapy. In this review, we discuss the potential of cell-free products such as the decellularized extracellular matrix, growth factors, extracellular vesicles and miRNAs in endogenous bone and dental regeneration.

A thermogelling organic-inorganic hybrid hydrogel with excellent printability, shape fidelity and cytocompatibility for 3D bioprinting

Alginates are the most commonly used bioink in biofabrication, but their rheological profiles makes it very challenging to perform real 3D printing. In this study, an advanced hybrid hydrogel ink was developed, a mixture of thermogelling diblock copolymer, alginate and clay i.e. Laponite XLG. The reversible thermogelling and shear thinning properties of the diblock copolymer in the ink system improves handling and 3D printability significantly. Various three-dimensional constructs, including suspended filaments, were printed successfully with high shape fidelity and excellent stackability. Subsequent ionic crosslinking of alginate fixates the printed scaffolds, while the diblock copolymer is washed out of the structure, acting as a fugitive material on the (macro)molecular level. Finally, cell-laden printing and culture over 21 days demonstrated good cytocompatibility and feasibility of the novel hybrid hydrogels for 3D bioprinting. We believe that the developed material could be interesting for a wide range of bioprinting applications including tissue engineering and drug screening, potentially enabling also other biological bioinks such as collagen, hyaluronic acid, decellularized extracellular matrix or cellulose based bioinks.

Towards organoid culture without Matrigel

Organoids—cellular aggregates derived from stem or progenitor cells that recapitulate organ function in miniature—are of growing interest in developmental biology and medicine. Organoids have been developed for organs and tissues such as the liver, gut, brain, and pancreas; they are used as organ surrogates to study a wide range of questions in basic and developmental biology, genetic disorders, and therapies. However, many organoids reported to date have been cultured in Matrigel, which is prepared from the secretion of Engelbreth-Holm-Swarm mouse sarcoma cells; Matrigel is complex and poorly defined. This complexity makes it difficult to elucidate Matrigel-specific factors governing organoid development. In this review, we discuss promising Matrigel-free methods for the generation and maintenance of organoids that use decellularized extracellular matrix (ECM), synthetic hydrogels, or gel-forming recombinant proteins.

The Regeneration of Large-Sized and Vascularized Adipose Tissue Using a Tailored Elastic Scaffold and dECM Hydrogels

A dome-shaped elastic poly (l-lactide-co-caprolactone) (PLCL) scaffold with a channel and pore structure was fabricated by a combinative method of 3D printing technology and the gel pressing method (13 mm in diameter and 6.5 mm in thickness) for patient-specific regeneration. The PLCL scaffold was combined with adipose decellularized extracellular matrix (adECM) and heart decellularized extracellular matrix (hdECM) hydrogels and human adipose-derived stem cells (hADSCs) to promote adipogenesis and angiogenesis. These scaffolds had mechanical properties similar to those of native adipose tissue for improved tissue regeneration. The results of the in vitro real-time PCR showed that the dECM hydrogel mixture induces adipogenesis. In addition, the in vivo study at 12 weeks demonstrated that the tissue-engineered PLCL scaffolds containing the hydrogel mixture (hdECM/adECM (80:20)) and hADSCs promoted angiogenesis and adipose tissue formation, and suppressed apoptosis. Therefore, we expect that our constructs will be clinically applicable as material for the regeneration of patient-specific large-sized adipose tissue.