Tethered TGF-β1 in a Hyaluronic Acid-Based Bioink for Bioprinting Cartilaginous Tissues

In 3D bioprinting for cartilage regeneration, bioinks that support chondrogenic development are of key importance. Growth factors covalently bound in non-printable hydrogels have been shown to effectively promote chondrogenesis. However, studies that investigate the functionality of tethered growth factors within 3D printable bioinks are still lacking. Therefore, in this study, we established a dual-stage crosslinked hyaluronic acid-based bioink that enabled covalent tethering of transforming growth factor-beta 1 (TGF‑β1). Bone marrow-derived mesenchymal stromal cells (MSCs) were cultured over three weeks in vitro, and chondrogenic differentiation of MSCs within bioink constructs with tethered TGF‑β1 was markedly enhanced, as compared to constructs with non-covalently incorporated TGF‑β1. This was substantiated with regard to early TGF‑β1 signaling, chondrogenic gene expression, qualitative and quantitative ECM deposition and distribution, and resulting construct stiffness. Furthermore, it was successfully demonstrated, in a comparative analysis of cast and printed bioinks, that covalently tethered TGF‑β1 maintained its functionality after 3D printing. Taken together, the presented ink composition enabled the generation of high-quality cartilaginous tissues without the need for continuous exogenous growth factor supply and, thus, bears great potential for future investigation towards cartilage regeneration. Furthermore, growth factor tethering within bioinks, potentially leading to superior tissue development, may also be explored for other biofabrication applications.

A G protein-coupled receptor is required in cartilaginous and dense connective tissues to maintain spine alignment

Adolescent idiopathic scoliosis (AIS) is the most common spine disorder affecting children worldwide, yet little is known about the pathogenesis of this disorder. Here, we demonstrate that genetic regulation of structural components of the axial skeleton, the intervertebral discs, and dense connective tissues (i.e., ligaments and tendons) are essential for the maintenance of spinal alignment. We show that the adhesion G protein-coupled receptor ADGRG6, previously implicated in human AIS association studies, is required in these tissues to maintain typical spine alignment in mice. Furthermore, we show that ADGRG6 regulates biomechanical properties of tendon and stimulates CREB signaling governing gene expression in cartilaginous tissues of the spine. Treatment with a cAMP agonist could mirror aspects of receptor function in culture, thus defining core pathways for regulating these axial cartilaginous and connective tissues. As ADGRG6 is a key gene involved in human AIS, these findings open up novel therapeutic opportunities for human scoliosis.

A G protein-coupled receptor is required in cartilaginous and dense connective tissues to maintain spine alignment

SummaryAdolescent idiopathic scoliosis (AIS) is the most common spine disorder affecting children worldwide, yet little is known about the pathogenesis of this disorder. Here, we demonstrate that genetic regulation of structural components of the axial skeleton, the intervertebral discs and dense connective tissues (e.g., ligaments and tendons), are essential for maintenance of spinal alignment. We show that the G-coupled protein receptor Adgrg6, previously implicated in human AIS association studies, is required in these tissues to maintain typical spine morphology. We show that Adgrg6 regulates biomechanical properties of tendon and stimulates CREB signaling governing gene expression in cartilaginous tissues of the spine. Treatment with an cAMP agonist was able to mirror aspects of receptor function in culture defining core pathways for regulation of these axial connective tissues. As ADGRG6 is a key gene involved in human AIS, these findings open up novel therapeutic opportunities for human scoliosis.HighlightsKnockout mice lacking Adgrg6 function in the tendons and ligaments of the spine develop perinatal-onset thoracic scoliosis.Loss of Adgrg6 function in cartilaginous tissues of the discs contribute to the incidence and severity of scoliosis.The loss of Adgrg6 function in spine tissues provide a model of construct validity for human adolescent idiopathic scoliosisFine tuning of the biomechanical properties of dense connective tissues is essential for maintaining spine alignment.

The strain-generated electrical potential in cartilaginous tissues: a role for piezoelectricity

The strain-generated potential (SGP) is a well-established mechanism in cartilaginous tissues whereby mechanical forces generate electrical potentials. In articular cartilage (AC) and the intervertebral disc (IVD), studies on the SGP have focused on fluid- and ionic-driven effects, namely Donnan, diffusion and streaming potentials. However, recent evidence has indicated a direct coupling between strain and electrical potential. Piezoelectricity is one such mechanism whereby deformation of most biological structures, like collagen, can directly generate an electrical potential. In this review, the SGP in AC and the IVD will be revisited in light of piezoelectricity and mechanotransduction. While the evidence base for physiologically significant piezoelectric responses in tissue is lacking, difficulties in quantifying the physiological response and imperfect measurement techniques may have underestimated the property. Hindering our understanding of the SGP further, numerical models to-date have negated ferroelectric effects in the SGP and have utilised classic Donnan theory that, as evidence argues, may be oversimplified. Moreover, changes in the SGP with degeneration due to an altered extracellular matrix (ECM) indicate that the significance of ionic-driven mechanisms may diminish relative to the piezoelectric response. The SGP, and these mechanisms behind it, are finally discussed in relation to the cell response.

Histological assessment of the quality of groundmeat semi-finished products

The article deals with the problem of quality of pork and beef groundmeat semi-finished products of A category. The research was conducted in the city of Perm in 2021. The study used organoleptic and histological research methods. The organoleptic analysis showed full compliance of the tested products with the requirements of regulatory documents. As a result of histological research, violations of GOST 32951-2014 requirements were recorded: in a number of samples, the mass fraction of skeletal muscles was in the ratio of 1:1 with adipose tissue. Most of the samples (85 %) included the presence of connective and cartilaginous tissues. The biological hazard of the tested samples of meat products was established – 100% contamination by parasites of the genus Sarcocystis spp was noted. The number of sarcocysts in the samples studied by us varied from 3 units in the preparation to 4 units in the field of view.

Evaluation of Parameters in PLA and PCL Scaffolds to be Used in Cartilaginous Tissues

The scopes of medical treatments involving organ transplants and implants for chronic problems and trauma have changed significantly. However, these procedures are subject to multiple problems. Recently, tissue engineering has been used to address them. The present study is framed in the field of tissue engineering, particularly cartilage tissue, and proposes the evaluation of geometric and impression parameters for the manufacture of scaffolds as a basis for the growth of cells through 3D impression techniques. These scaffolds are highly porous three-dimensional supports that house donated or himself patient cells, providing a surface where the cells can adhere and proliferate. In the methodology, geometric and pore size variables are defined for scaffolding modeling by using CAD techniques and standardization of the printing process with standard 3D printers and accessible materials. The results showed that material flow, printing temperature, printing speed and ventilation are the most influential parameters in the manufacture of scaffolds. Additionally, it was found micrometric variations between the modeled design and the printing result. These scaffolds will subsequently be subjected to in vitro cell culture evaluating the adherence, division, and proliferation of the cells.