Enhanced Piezoelectric Fibered Extracellular Matrix to Promote Cardiomyocyte Maturation and Tissue Formation: A 3D Computational Model

Electrowriting patterns and electric field harness directional cell migration for skin wound healing

Directional cell migration is a crucial step in wound healing, influenced by electrical and topographic stimulations. However, the underlying mechanism and the combined effects of these two factors on cell migration remain unclear. This study explores cell migration under various combinations of guided straight line (SL) spacing, conductivity, and the relative direction of electric field (EF) and SL. Electrowriting is employed to fabricate conductive (multiwalled carbon nanotube/polycaprolactone (PCL)) and nonconductive (PCL) SL, with narrow (50 μm) and wide (400 μm) spacing that controls the topographic stimulation strength. Results show that various combinations of electrical and topographic stimulation yield significantly distinct effects on cell migration direction and speed; cells migrate fastest with the most directivity in the case of conductive, narrow-spacing SL parallel to EF. A physical model based on intercellular interactions is developed to capture the underlying mechanism of cell migration under SL and EF stimulations, in agreement with experimental observations. In vivo skin wound healing assay further confirmed that the combination of EF (1 V cm-1) and parallelly aligned conductive fibers accelerated the wound healing process. This study presents a promising approach to direct cell migration and enhance wound healing by optimizing synergistic electrical and topographic stimulations.

Computational modeling of multiple myeloma interactions with resident bone marrow cells

The interaction of multiple myeloma with bone marrow resident cells plays a key role in tumor progression and the development of drug resistance. The tumor cell response involves contact-mediated and paracrine interactions. The heterogeneity of myeloma cells and bone marrow cells makes it difficult to reproduce this environment in in-vitro experiments. The use of in-silico established tools can help to understand these complex problems. In this article, we present a computational model based on the finite element method to define the interactions of multiple myeloma cells with resident bone marrow cells. This model includes cell migration, which is controlled by stress-strain equilibrium, and cell processes such as proliferation, differentiation, and apoptosis. A series of computational experiments were performed to validate the proposed model. Cell proliferation by the growth factor IGF-1 is studied for different concentrations ranging from 0-10 ng/mL. Cell motility is studied for different concentrations of VEGF and fibronectin in the range of 0-100 ng/mL. Finally, cells were simulated under a combination of IGF-1 and VEGF stimuli whose concentrations are considered to be dependent on the cancer-associated fibroblasts in the extracellular matrix. Results show a good agreement with previous in-vitro results. Multiple myeloma growth and migration are shown to correlate linearly to the IGF-1 stimuli. These stimuli are coupled with the mechanical environment, which also improves cell growth. Moreover, cell migration depends on the fiber and VEGF concentration in the extracellular matrix. Finally, our computational model shows myeloma cells trigger mesenchymal stem cells to differentiate into cancer-associated fibroblasts, in a dose-dependent manner.

Stem Cell Studies in Cardiovascular Biology and Medicine: A Possible Key Role of Macrophages

Simple Summary

Stem cells are used in cardiovascular biology and biomedicine and this field of research is expanding. Two types of stem cells have been used in research: induced pluripotent and somatic stem cells. Induced pluripotent stem cells (iPSCs) are similar to embryonic stem cells (ESCs) in that they can differentiate into somatic cells. Bone marrow stem/stromal cells (BMSCs), adipose-derived stem cells (ASCs), and cardiac stem cells (CSCs) are somatic stem cells that have been used for cardiac regeneration. Recent studies have indicated that exosomes and vesicles from BMSCs and ASCs can be used in regenerative medicine and diagnostics. Chemokines and exosomes can contribute to the communication between inflammatory cells and stem cells to differentiate stem cells into the cell types required for tissue regeneration or repair. In this review, we address these issues based on our research and previous publications.

Abstract

Stem cells are used in cardiovascular biology and biomedicine, and research in this field is expanding. Two types of stem cells have been used in research: induced pluripotent and somatic stem cells. Stem cell research in cardiovascular medicine has developed rapidly following the discovery of different types of stem cells. Induced pluripotent stem cells (iPSCs) possess potent differentiation ability, unlike somatic stem cells, and have been postulated for a long time. However, differentiating into adult-type mature and functional cardiac myocytes (CMs) remains difficult. Bone marrow stem/stromal cells (BMSCs), adipose-derived stem cells (ASCs), and cardiac stem cells (CSCs) are somatic stem cells used for cardiac regeneration. Among somatic stem cells, bone marrow stem/stromal cells (BMSCs) were the first to be discovered and are relatively well-characterized. BMSCs were once thought to have differentiation ability in infarcted areas of the heart, but it has been identified that paracrine cytokines and micro-RNAs derived from BMSCs contributed to that effect. Moreover, vesicles and exosomes from these cells have similar effects and are effective in cardiac repair. The molecular signature of exosomes can also be used for diagnostics because exosomes have the characteristics of their origin cells. Cardiac stem cells (CSCs) differentiate into cardiomyocytes, smooth muscle cells, and endothelial cells, and supply cardiomyocytes during myocardial infarction by differentiating into newly formed cardiomyocytes. Stem cell niches and inflammatory cells play important roles in stem cell regulation and the recovery of damaged tissues. In particular, chemokines can contribute to the communication between inflammatory cells and stem cells. In this review, we present the current status of this exciting and promising research field.

Impact of Electrospun Piezoelectric Core-Shell PVDFhfp/PDMS Mesh on Tenogenic and Inflammatory Gene Expression in Human Adipose-Derived Stem Cells: Comparison of Static Cultivation with Uniaxial Cyclic Tensile Stretching

Specific microenvironments can trigger stem cell tenogenic differentiation, such as specific substrates or dynamic cell cultivation. Electrospun meshes composed by core–shell fibers (random or aligned; PDMS core; piezoelectric PVDFhfp shell) were fabricated by coaxial electrospinning. Elastic modulus and residual strain were assessed. Human ASCs were seeded on such scaffolds either under static conditions for 1 week or with subsequent 10% dynamic stretching for 10,800 cycles (1 Hz, 3 h), assessing load elongation curves in a Bose^® bioreactor system. Gene expression for tenogenic expression, extracellular matrix, remodeling, pro-fibrotic and inflammatory marker genes were assessed (PCR). For cell-seeded meshes, the E modulus increased from 14 ± 3.8 MPa to 31 ± 17 MPa within 3 h, which was not observed for cell-free meshes. Random fibers resulted in higher tenogenic commitment than aligned fibers. Dynamic cultivation significantly enhanced pro-inflammatory markers. Compared to ASCs in culture flasks, ASCs on random meshes under static cultivation showed a significant upregulation of Mohawk, Tenascin-C and Tenomodulin. The tenogenic commitment expressed by human ASCs in contact with random PVDFhfp/PDMS paves the way for using this novel highly elastic material as an implant to be wrapped around a lacerated tendon, envisioned as a functional anti-adhesion membrane.