Mechanotransduction in tissue engineering: Insights into the interaction of stem cells with biomechanical cues

Cocultured amniotic stem cells and cardiomyocytes in a 3-D acellular heart patch reduce the infarct size and left ventricle remodeling: promote angiogenesis in a porcine acute myocardial infarction model

BACKGROUND

Acute myocardial infarction (AMI) induces significant myocardial damage, ultimately leading to heart failure as the surrounding healthy myocardial tissue undergoes progressive deterioration due to excessive mechanical stress.

METHODS

This study aimed to investigate myocardial regeneration in a porcine model of AMI using an acellular amniotic membrane with fibrin-termed an amnion bilayer (AB) or heart patch-as a cellular delivery system using porcine amniotic stem cells (pASCs) and autologous porcine cardiomyocytes (pCardios). Fifteen pigs (aged 2-4 months, weighing 50-60 kg) were randomly assigned to three experimental groups (n = 5): control group (AMI induction only), pASC group (pASC transplantation only), and coculture group (pASC and pCardio transplantation). AMI was induced via posterior left ventricular artery ligation and confirmed through standard biomarkers. After eight weeks, histological and molecular analyses were conducted to assess myocardial regeneration.

RESULTS

Improvement in regional wall motion abnormality (RWMA) was observed in 60% of the coculture group, 25% of the pASC group, and none in the control group. Histological analysis of the control group revealed extensive fibrosis with pronounced lipomatosis, particularly at the infarct center. In contrast, pASC and coculture groups exhibited minimal fibrotic scarring at both the infarct center and border regions. Immunofluorescence analysis demonstrated positive α-actinin expression in both the pASC and coculture groups, with the coculture group displaying sarcomeric structures-an organization absent in control group. RNA expression levels of key cardiomyogenic markers, including cardiac troponin T (cTnT), myosin heavy chain (MHC), and Nkx2.5, were significantly elevated in the treatment groups compared to the controls, with the coculture group exhibiting the highest MHC expression. The expression of c-Kit was also increased in both treatment groups relative to the control. Conversely, apoptotic markers p21 and Caspase-9 were highest in the control group, while coculture group exhibited the lowest p53 expression.

CONCLUSION

Epicardial transplantation of an acellular amniotic heart patch cocultured with cardiomyocytes and pASCs demonstrated superior cardiomyogenesis after eight weeks compared to pASC transplantation alone or control conditions. The coculture system was found to enhance the cardiac regeneration process, as evidenced by improved RWMA, distinct sarcomeric organization, reduced fibrotic scarring, and lower apoptotic gene expression.

Mechanotransduction in Development: A Focus on Angiogenesis

Cells respond to external mechanical cues and transduce these forces into biological signals. This process is known as mechanotransduction and requires a group of proteins called mechanosensors. This peculiar class of receptors include extracellular matrix proteins, plasma membrane proteins, the cytoskeleton and the nuclear envelope. These cell components are responsive to a wide spectrum of physical cues including stiffness, tensile force, hydrostatic pressure and shear stress. Among mechanotransducers, the Transient Receptor Potential (TRP) and the PIEZO family members are mechanosensitive ion channels, coupling force transduction with intracellular cation transport. Their activity contributes to embryo development, tissue remodeling and repair, and cell homeostasis. In particular, vessel development is driven by hemodynamic cues such as flow direction and shear stress. Perturbed mechanotransduction is involved in several pathological vascular phenotypes including hereditary hemorrhagic telangiectasia. This review is conceived to summarize the most recent findings of mechanotransduction in development. We first collected main features of mechanosensitive proteins. However, we focused on the role of mechanical cues during development. Mechanosensitive ion channels and their function in vascular development are also discussed, with a focus on brain vessel morphogenesis.

Regenerative Aesthetics: A Genuine Frontier or Just a Facet of Regenerative Medicine: A Systematic Review

BACKGROUND

Regenerative aesthetics claims to enhance cosmetic outcomes through advanced biological interventions like Stem cell and Exosome therapy, Polydeoxyribonucleotide (PDRN), Photobiomodulation, bioactive peptides and treatment for cellular senescence yet lacks substantial scientific and regulatory validation.

OBJECTIVE

To evaluate the scientific and clinical foundations of regenerative medicine techniques in non-surgical aesthetics and assess the legitimacy of regenerative aesthetics as a medical specialty.

METHODS

A systematic review was conducted according to PRISMA guidelines, searching databases including PubMed, Scopus, and Web of Science for studies published in the last ten years. We included 19 studies, comprising 14 randomized controlled trials (RCTs) and 5 prospective studies, focusing on interventions that purportedly use regenerative medicine principles in aesthetic applications.

RESULTS

The review highlights a prevalent gap in molecular and clinical evidence supporting the efficacy and safety of regenerative aesthetics. Despite the robust design of the included RCTs and prospective studies, there remains a significant lack of consistent, high-quality evidence proving the effectiveness of these interventions. Issues such as inadequate reporting, unclear molecular mechanisms, and absence of long-term safety data were common.

CONCLUSION

The field of regenerative aesthetics lacks the necessary scientific rigour and regulatory compliance to be recognized as a legitimate medical specialty. This review underscores the need for stringent scientific validation and regulatory oversight to ensure patient safety and treatment efficacy before these techniques can be recommended for clinical use.

LEVEL OF EVIDENCE II

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Use of Hydrogels in Regenerative Medicine: Focus on Mechanical Properties

Bioengineered materials represent an innovative option to support the regenerative processes of damaged tissues, with the final objective of creating a functional environment closely mimicking the native tissue. Among the different available biomaterials, hydrogels represent the solution of choice for tissue regeneration, thanks to the easy synthesis process and the highly tunable physical and mechanical properties. Moreover, hydrogels are biocompatible and biodegradable, able to integrate in biological environments and to support cellular interactions in order to restore damaged tissues' functionality. This review offers an overview of the current knowledge concerning hydrogel synthesis and characterization and of the recent achievements in their experimental use in supporting skin, bone, cartilage, and muscle regeneration. The currently available in vitro and in vivo results are of great interest, highlighting the need for carefully designed and controlled preclinical studies and clinical trials to support the transition of these innovative biomaterials from the bench to the bedside.

Collagen-rich liver-derived extracellular matrix hydrogels augment survival and function of primary rat liver sinusoidal endothelial cells and hepatocytes

Liver sinusoidal endothelial cells (LSECs) are key targets for addressing metabolic dysfunction-associated steatotic liver disease (MASLD). However, isolating and culturing primary LSECs is challenging due to rapid dedifferentiation, resulting in loss of function. The extracellular matrix (ECM) likely plays a crucial role in maintaining the fate and function of LSECs. In this study, we explored the influence of liver-ECM (L-ECM) on liver cells and developed culture conditions that maintain the differentiated function of liver cells in vitro for prolonged periods. Porcine liver-derived L-ECM, containing 34.9 % protein, 0.045 % glycosaminoglycans, and negligible residual DNA (41.2 ng/mg), was utilized to culture primary rat liver cells in generated hydrogels. Proteomic analyses and molecular weight distribution of proteins of solubilized L-ECM revealed the typical diverse ECM core matrisome, with abundant collagens. L-ECM hydrogels showed suitable stiffness and stress relaxation properties. Furthermore, we demonstrated that collagen-rich L-ECM hydrogels enhanced LSECs' and hepatocytes' viability, and reduced the dedifferentiation rate of LSECs. In addition, hepatocyte function was maintained longer by culture on L-ECM hydrogels compared to traditional culturing. These beneficial effects are likely attributed to the bioactive macromolecules including collagens, and mechanical and microarchitectural properties of the L-ECM hydrogels.

Advances in Shear Stress Stimulation of Stem Cells: A Review of the Last Three Decades

Stem cells are widely used in scientific research because of their ability to self-renew and differentiate into a variety of specialized cell types needed for body functions. However, the self-renewal and differentiation of stem cells are regulated by various stimuli, with mechanical stimulation being particularly notable due to its ability to mimic the physical environment in the body. This study systematically collected 2638 research papers published between 1994 and 2024, employing tools such as VOSviewer, CiteSpace, and GraphPad Prism to uncover research hotspots, publication trends, and collaboration networks. The results indicate a yearly increase in global research on the shear stress stimulation of stem cells, with significant contributions from the United States and China in terms of research investment and output. Future research directions include a deeper understanding of the mechanisms underlying mechanical stimulation's effects on stem cell differentiation, the development of new materials and scaffold designs to better replicate the natural cellular environment, and advancements in regenerative medicine. Despite considerable progress, challenges remain in translating basic research findings into clinical applications.

Using Nanoscale Passports To Understand and Unlock Ion Channels as Gatekeepers of the Cell

Natural ion channels are proteins embedded in the cell membrane that control many aspects of cell and human physiology by acting as gatekeepers, regulating the flow of ions in and out of cells. Advances in nanotechnology have influenced the methods for studying ion channels in vitro, as well as ways to unlock the delivery of therapeutics by modulating them in vivo. This review provides an overview of nanotechnology-enabled approaches for ion channel research with a focus on the synthesis and applications of synthetic ion channels. Further, the uses of nanotechnology for therapeutic applications are critically analyzed. Finally, we provide an outlook on the opportunities and challenges at the intersection of nanotechnology and ion channels. This work highlights the key role of nanoscale interactions in the operation and modulation of ion channels, which may prompt insights into nanotechnology-enabled mechanisms to study and exploit these systems in the near future.

Delivery of Stem Cells and BMP-2 With Functionalized Self-Assembling Peptide Enhances Regeneration of Infarcted Myocardium

Stem cell transplantation is a promising therapeutic strategy for myocardial infarction (MI). However, engraftment, survival and differentiation of the transplanted stem cells in ischemic and inflammatory microenvironment are poor. We designed a novel self-assembly peptide (SAP) by modifying the peptide RADA16 with cell-adhesive motif and BMP-2 (bone morphogenetic protein-2)-binding motif. Effects of the functionalized SAP on adhesion, survival and differentiation of c-kit+ MSCs (mesenchymal stem cells) were examined. Myocardial regeneration, neovascularization and cardiac function were assessed after transplantation of the SAP loading c-kit+ MSCs and BMP-2 in rat MI models. The SAP could spontaneously assemble into well-ordered nanofibrous scaffolds. The cells adhered to the SAP scaffolds and spread well. The SAP protected the cells in the condition of hypoxia and serum deprivation. Following degradation of the SAP, BMP-2 was released sustainedly and induced c-kit+ MSCs to differentiate into cardiomyocytes. At four weeks after transplantation of the SAP loading c-kit+ MSCs and BMP-2, myocardial regeneration and angiogenesis were enhanced, and cardiac function was improved significantly. The cardiomyocytes differentiated from the engrafted c-kit+ MSCs were increased markedly. The differentiated cells connected with recipient cardiomyocytes to form gap junctions. Collagen volume was decreased dramatically. These results suggest that the functionalized SAP promotes engraftment, survival and differentiation of stem cells effectively. Local sustained release of BMP-2 with SAP is a viable strategy to enhance differentiation of the engrafted stem cells and repair of the infarcted myocardium.

TENET: Triple-enhancement based graph neural network for cell-cell interaction network reconstruction from spatial transcriptomics

Cellular communication relies on the intricate interplay of signaling molecules, forming the Cell-cell Interaction network (CCI) that coordinates tissue behavior. Researchers have shown the capability of shallow neural networks in reconstructing CCI, given molecules' abundance in the Spatial Transcriptomics (ST) data. When encountering situations such as sparse connections in CCI and excessive noise, the susceptibility of shallow networks to these factors significantly impacts the accuracy of CCI reconstruction, resulting in subpar results. To reconstruct a more comprehensive and accurate CCI, we propose a novel method named Triple-Enhancement based Graph Neural Network (TENET). In TENET, three progressive enhancement mechanisms build upon each other, creating a cumulative effect. This approach can ensure the ability to capture valuable features in limited data and amplify the noise signal to facilitate the denoising effect. Additionally, the whole architecture guides the decoding reconstruction phase with integrated knowledge, which leverages the accumulated insights from each stage of enhancement to ensure a refined and comprehensive CCI reconstruction. The presented TENET has been implemented and tested on both real and synthetic ST datasets. Averagely, the CCI reconstruction using TENET achieves a 9.61% improvement in Average Precision (AP) and a 7.32% improvement in Area Under the Receiver Operating Characteristic (AUROC) compared to the existing state-of-the-art (SOTA) method. The source code and data are available at https://github.com/Yujian-Lee/TENET.

Adipose-Derived Stem Cells: Angiogenetic Potential and Utility in Tissue Engineering

Adipose tissue (AT) is a large and important energy storage organ as well as an endocrine organ with a critical role in many processes. Additionally, AT is an enormous and easily accessible source of multipotent cell types used in our day for all types of tissue regeneration. The ability of adipose-derived stem cells (ADSCs) to differentiate into other types of cells, such as endothelial cells (ECs), vascular smooth muscle cells, or cardiomyocytes, is used in tissue engineering in order to promote/stimulate the process of angiogenesis. Being a key for future successful clinical applications, functional vascular networks in engineered tissue are targeted by numerous in vivo and ex vivo studies. The article reviews the angiogenic potential of ADSCs and explores their capacity in the field of tissue engineering (TE).

The Role of Mechanotransduction in Contact Inhibition of Locomotion and Proliferation

Contact inhibition (CI) represents a crucial tumor-suppressive mechanism responsible for controlling the unbridled growth of cells, thus preventing the formation of cancerous tissues. CI can be further categorized into two distinct yet interrelated components: CI of locomotion (CIL) and CI of proliferation (CIP). These two components of CI have historically been viewed as separate processes, but emerging research suggests that they may be regulated by both distinct and shared pathways. Specifically, recent studies have indicated that both CIP and CIL utilize mechanotransduction pathways, a process that involves cells sensing and responding to mechanical forces. This review article describes the role of mechanotransduction in CI, shedding light on how mechanical forces regulate CIL and CIP. Emphasis is placed on filamin A (FLNA)-mediated mechanotransduction, elucidating how FLNA senses mechanical forces and translates them into crucial biochemical signals that regulate cell locomotion and proliferation. In addition to FLNA, trans-acting factors (TAFs), which are proteins or regulatory RNAs capable of directly or indirectly binding to specific DNA sequences in distant genes to regulate gene expression, emerge as sensitive players in both the mechanotransduction and signaling pathways of CI. This article presents methods for identifying these TAF proteins and profiling the associated changes in chromatin structure, offering valuable insights into CI and other biological functions mediated by mechanotransduction. Finally, it addresses unanswered research questions in these fields and delineates their possible future directions.

Electroconductive Nanofibrous Scaffolds Enable Neuronal Differentiation in Response to Electrical Stimulation without Exogenous Inducing Factors

Among the various biochemical and biophysical inducers for neural regeneration, electrical stimulation (ES) has recently attracted considerable attention as an efficient means to induce neuronal differentiation in tissue engineering approaches. The aim of this in vitro study was to develop a nanofibrous scaffold that enables ES-mediated neuronal differentiation in the absence of exogenous soluble inducers. A nanofibrous scaffold composed of polycaprolactone (PCL), poly-L-lactic acid (PLLA), and single-walled nanotubes (SWNTs) was fabricated via electrospinning and its physicochemical properties were investigated. The cytocompatibility of the electrospun composite with the PC12 cell line and bone marrow-derived mesenchymal stem cells (BMSCs) was investigated. The results showed that the PCL/PLLA/SWNT nanofibrous scaffold did not exhibit cytotoxicity and supported cell attachment, spreading, and proliferation. ES was applied to cells cultured on the nanofibrous scaffolds at different intensities and the expression of the three neural markers (Nestin, Microtubule-associated protein 2, and β tubulin-3) was evaluated using RT-qPCR analysis. The results showed that the highest expression of neural markers could be achieved at an electric field intensity of 200 mV/cm, suggesting that the scaffold in combination with ES can be an efficient tool to accelerate neural differentiation in the absence of exogenous soluble inducers. This has important implications for the regeneration of nerve injuries and may provide insights for further investigations of the mechanisms underlying ES-mediated neuronal commitment.