Abstract P1136: Amino Acid Availability Regulates Differentiation Of HIPSC-derived Cardiomyocytes In A Protein-free System

Traditional protocols for the differentiation of hiPSC-derived cardiomyocytes (hiPSC-CMs) rely on complex media and the use of animal or recombinant proteins either directly or in supplements, such as B27, to obtain tissue monolayers. This fact decreases their reproducibility, while potentially increasing their costs and limiting higher-throughput production of cardiomyocytes for applications in both regenerative medicine, disease modeling, and pharmacological screenings. Albumin/serum-free protocols have been developed but produce cells with limited functionality and at lower yields, despite them being TNNT2-positive. We previously demonstrated it is possible to simplify the differentiation protocol utilizing a stepwise approach and combining time-point interventions with small molecules or nutritional inputs. Here, we performed a thorough screening of commercial media and their suitability for differentiation of hiPSC-CMs. We identified suitable basal media formulations and developed a novel protein-free differentiation protocol (PFDM) for generating hiPSC-CMs that preserves purity, yield, morphology, and functionality while reducing the cost of the differentiation process. PFDM also enabled the identification of nutritional requirements essential for cardiac differentiation and allowed a detailed investigation into how some common components supplemented during hiPSC-CM differentiation impact tissue morphology and contractility. We showed that non-essential amino acids regulate differentiation in a time-dependent manner. Similarly, antioxidant agents such as sodium pyruvate and ascorbic acid, while essential for differentiation, are potentially harmful during early cardiac mesoderm induction. Lastly, we validated this PFDM methodology in 35 control and patient-derived hiPSC lines, with monolayer differentiations in 6- and 12-well plates, 15 cm dishes, in addition to differentiations in 3D using 100- and 250-mL spinner flasks.

Sirtuin inhibition and anti-cancer activities of ethyl 2-benzimidazole-5-carboxylate derivatives

New benzimidazoles were synthesized based on the previously identified sirtuin inhibitor BZD9L1. The compounds were screened for their sirtuin (SIRT1, SIRT2 and SIRT3) inhibitory activities. Compound BZD9Q1 was determined to be a pan-SIRT1-3 inhibitor. Furthermore, the proliferation of various cancer cells was inhibited by BZD9Q1. It was shown that BZD9Q1 elicits a cytostatic effect by inducing cell cycle arrest at the G₂/M phase while also showing a prominent induction of apoptosis against oral cancer cells.

Anterior Cruciate Ligament: Structure, Injuries and Regenerative Treatments

Anterior cruciate ligament (ACL) is one of the most vulnerable ligaments of the knee. ACL impairment results in episodic instability, chondral and meniscal injury and early osteoarthritis. The poor self-healing capacity of ACL makes surgical treatment inevitable. Current ACL reconstructions include a substitution of torn ACL via biological grafts such as autograft, allograft. This review provides an insight of ACL structure, orientation and properties followed by comparing the performance of various constructs that have been used for ACL replacement. New approaches, undertaken to induce ACL regeneration and fabricate biomimetic scaffolds, are also discussed.

A Novel Strategy for Softening Gelatin-Bioactive-Glass Hybrids

The brittle structure of polymer-bioactive-glass hybrids is a hurdle for their biomedical applications. To address this issue here, we developed a novel method to cease the overcondensation of bioactive-glass by polymer cross-linking. Here, an organosilane-functionalized gelatin methacrylate (GelMA) is covalently bonded to a bioactive-glass during the sol-gel process, and the condensation of silica networks is controlled by photo-cross-linking of GelMA. The physicochemical properties and mechanical strength of these hybrids are tunable by the incorporation of secondary cross-linking agents. These hydrogels display elastic properties with ultimate compression strain above 0.2 mm·mm(-1) and tunable compressive modulus in the range of 42-530 kPa. In addition, these hydrogels are bioactive because they promoted the alkaline phosphatase activity of bone progenitor cells. They are also well-tolerated in the mice subcutaneous model. Therefore, our method is efficient for the prevention of overcondensation and allows preparation of soft bioactive hydrogels from organic-inorganic matrices, suitable for soft and hard tissue regeneration.

Biomedical Applications of Biodegradable Polyesters

The focus in the field of biomedical engineering has shifted in recent years to biodegradable polymers and, in particular, polyesters. Dozens of polyester-based medical devices are commercially available, and every year more are introduced to the market. The mechanical performance and wide range of biodegradation properties of this class of polymers allow for high degrees of selectivity for targeted clinical applications. Recent research endeavors to expand the application of polymers have been driven by a need to target the general hydrophobic nature of polyesters and their limited cell motif sites. This review provides a comprehensive investigation into advanced strategies to modify polyesters and their clinical potential for future biomedical applications.