Growth factor regulation of proliferation and survival of multipotential stromal cells

Optimizing interleukin-6 and 8 expression, clarification and purification in plant cell packs and plants for application in advanced therapy medicinal products and cellular agriculture

Healthcare and nutrition are facing a paradigm shift in light of advanced therapy medicinal products (ATMPs) and cellular agriculture options respectively. Both options heavily rely on some sort of animal cell culture, e.g. autologous stem cells. These cultures require various growth factors, such as interleukin-6 and 8 (IL-6/8), in a pure, safe and sustainable form that can be provided in a scalable manner. Plants seem well suited for this task because purification of small proteins can be readily achieved by membrane separation, human/animal pathogens do not replicate in plants and production can be scaled up using in-door farming or agricultural practices. Here, we illustrate this capacity by first optimizing the codon usage of IL-6/8 for translation in Nicotiana spp., as well as testing the effect of untranslated regions and product targeting to different sub-cellular compartments on expression in a high-throughput plant cell pack (PCP) assay. In the chloroplast, IL-6 accumulated up to 6.9±3.8 (SD, n=2) and 14.4±7.4 mg kg-1 (SD, n=5) were observed in case of IL-8. When transferring IL-8 expression into whole plants, accumulation was 12.3±1.5 mg kg-1 (SD, n=3). After extraction and clarification, IL-8 was purified using a two-stage process consisting of an ultrafiltration/diafiltration step with 100 kDa and 10 kDa cut off membranes followed by an IMAC polishing step. The purity, yield and recovery were 97.8%, 6.6 mg kg-1 and 38%, respectively. We evaluated the ability of the proposed purification process to remove endotoxins to ensure the compatibility of plant-made growth factors with cell culture.

A comprehensive review and advanced biomolecule-based therapies for osteoporosis

BACKGROUND

The prevalence of osteoporosis (OP) on a global scale is significantly elevated that causes life threatening issues. The potential of groundbreaking biomolecular therapeutics in the field of OP is highly encouraging. The administration of biomolecular agents has the potential to mitigate the process of bone demineralization while concurrently augmenting the regenerative capacity of bone tissue, thereby facilitating a personalized therapeutic approach. Biomolecules-based therapies showed promising results in term of bone mass protection and restoration in OP.

AIM OF REVIEW

We summarized the recent biomolecular therapies with notable progress in clinical, demonstrating the potential to transform illness management. These treatments frequently utilize different biomolecule based strategies. Biomolecular therapeutics has a targeted character, which results in heightened specificity and less off-target effects, ultimately leading to increased patient outcomes. These aspects have the capacity to greatly enhance the management of OP, thus resulting in a major enhancement in the quality of life encountered by individuals affected by this condition.

Early Stages of Ex Vivo Collagen Glycation Disrupt the Cellular Interaction and Its Remodeling by Mesenchymal Stem Cells-Morphological and Biochemical Evidence

Mesenchymal stem cells (MSCs), pivotal for tissue repair, utilize collagen to restore structural integrity in damaged tissue, preserving its organization through concomitant remodeling. The non-enzymatic glycation of collagen potentially compromises MSC communication, particularly upon advancing the process, underlying various pathologies such as late-stage diabetic complications and aging. However, an understanding of the impact of early-stage collagen glycation on MSC interaction is lacking. This study examines the fate of in vitro glycated rat tail collagen (RTC) upon exposure to glucose for 1 or 5 days in contact with MSCs. Utilizing human adipose tissue-derived MSCs (ADMSCs), we demonstrate their significantly altered interaction with glycated collagen, characterized morphologically by reduced cell spreading, diminished focal adhesions formation, and attenuated development of the actin cytoskeleton. The morphological findings were confirmed by ImageJ 1.54g morphometric analysis with the most significant drop in the cell spreading area (CSA), from 246.8 μm2 for the native collagen to 216.8 μm2 and 163.7 μm2 for glycated ones, for 1 day and 5 days, respectively, and a similar trend was observed for cell perimeter 112.9 μm vs. 95.1 μm and 86.2 μm, respectively. These data suggest impaired recognition of early glycated collagen by integrin receptors. Moreover, they coincide with the reduced fibril-like reorganization of adsorbed FITC-collagen (indicating impaired remodeling) and a presumed decreased sensitivity to proteases. Indeed, confirmatory assays reveal diminished FITC-collagen degradation for glycated samples at 1 day and 5 days by attached cells (22.8 and 30.4%) and reduced proteolysis upon exogenous collagenase addition (24.5 and 40.4%) in a cell-free system, respectively. The mechanisms behind these effects remain uncertain, although differential scanning calorimetry confirms subtle structural/thermodynamic changes in glycated collagen.

Essential growth factor receptors for fibroblast homeostasis and activation: Fibroblast Growth Factor Receptor (FGFR), Platelet Derived Growth Factor Receptor (PDGFR), and Transforming Growth Factor β Receptor (TGFβR)

Fibroblasts are cells of mesenchymal origin that are found throughout the body. While these cells have several functions, their integral roles include maintaining tissue architecture through the production of key extracellular matrix components, and participation in wound healing after injury. Fibroblasts are also key mediators in disease progression during fibrosis, cancer, and other inflammatory diseases. Under these perturbed states, fibroblasts can activate into inflammatory fibroblasts or contractile myofibroblasts. Fibroblasts require various growth factors and mitogenic molecules for survival, proliferation, and differentiation. While the activity of mitogenic growth factors on fibroblasts in vitro was characterized as early as the 1970s, the proliferation and differentiation effects of growth factors on these cells in vivo are unclear. Recent work exploring the heterogeneity of fibroblasts raises questions as to whether all fibroblast cell states exhibit the same growth factor requirements. Here, we will examine and review existing studies on the influence of fibroblast growth factor receptors (FGFRs), platelet-derived growth factor receptors (PDGFRs), and transforming growth factor β receptor (TGFβR) on fibroblast cell states.

Characterizing the Immune Environment in Peritoneal Carcinomatosis: Insights for Novel Immunotherapy Strategies

BACKGROUND OR PURPOSE

Carcinomatosis, a distinct pattern of metastatic cancer in the peritoneal cavity, poses challenges for treatment and has limited therapeutic options. Understanding the immune environment of peritoneal surface malignancies is crucial for developing effective immunotherapeutic approaches. This study characterizes soluble immune mediators in the peritoneal fluid of patients with and without carcinomatosis to identify targets for novel treatment strategies.

PATIENTS AND METHODS

Serum and peritoneal fluid samples were collected from surgical patients, and a multianalyte analysis was performed using the Luminex platform. Patient characteristics, tumor sites, and sample collection details were recorded. Soluble immune mediator levels were measured and compared between peritoneal fluid and serum samples and among clinical subgroups. Statistical analysis was conducted to assess differences in analyte concentrations and correlations between samples.

RESULTS

There were 39 patients included in the study, with varying surgical indications. Significant differences were observed in soluble immune mediator levels between peritoneal fluid and serum, with peritoneal fluid exhibiting lower concentrations. Carcinomatosis was associated with elevated levels of proinflammatory mediators, including IL-6 and IL-8, while adaptive immune response markers were low in peritoneal fluid.

CONCLUSIONS

The peritoneal immune microenvironment in carcinomatosis favors innate immunity, presenting a challenging environment for effective antitumor response. High levels of proinflammatory mediators suggest potential targets for intervention, such as the IL-6 axis, FGF2, IL-8, and CCL2; these could be explored as potential mitigators of malignant ascites and enhance anti-tumor immune responses. These findings provide valuable insights for developing immunotherapy strategies and improving outcomes in patients with peritoneal carcinomatosis.

ITIH5 inhibits proliferation, adipogenic differentiation, and secretion of inflammatory cytokines of human adipose stem cells-A new key in treating obesity?

Inter-α-trypsin inhibitor heavy chain 5 (ITIH5) is widely expressed in the human body, and it is detected to be particularly abundant in adipose tissue. ITIH5 expression is increased in people with obesity compared to lean persons and is decreased by diet-induced weight loss. This suggests that ITIH5 may be involved in the development of adiposity and clinical metabolic variables, although its exact function remains unknown. We measured the protein concentration of ITIH5 in adipose samples from patients undergoing abdominoplasty and tested for correlation with the subjects' BMI as well as inflammatory mediators. We stimulated human adipose stem cells (ASCs) with recombinant (r)ITIH5 protein and tested for an effect on proliferation, differentiation, and immunosuppressive properties when the cells were exposed to an artificial inflammatory environment. We found positive correlations between ITIH5 levels and the BMI (p < .001) as well as concentrations of inflammatory cytokines (TNF-α, IL-6, and MCP-1) in adipose tissue (p < .01). Application of the rITIH5 protein inhibited both proliferation (p < .001) and differentiation of ASCs. Especially, the development of mature adipocytes was reduced by over 50%. Moreover, rITIH5 decreased the release of IL-6 and MCP-1 when the cells were exposed to TNF-α and IL-1β (p < .001). Our data suggest that ITIH5 is an adipokine that is increasingly released during human adipose tissue development, acting as a regulator that inhibits proliferation and adipogenic differentiation of ASCs. ITIH5 thus presents itself as a positive regulator of adipose tissue homeostasis, possibly protecting against both hyperplasia and hypertrophy of adipose tissue and the associated chronic inflammation.

A cost-effective and enhanced mesenchymal stem cell expansion platform with internal plasma-activated biofunctional interfaces

Mesenchymal stem cells (MSCs) used for clinical applications require in vitro expansion to achieve therapeutically relevant numbers. However, conventional planar cell expansion approaches using tissue culture vessels are inefficient, costly, and can trigger MSC phenotypic and functional decline. Here we present a one-step dry plasma process to modify the internal surfaces of three-dimensional (3D) printed, high surface area to volume ratio (high-SA:V) porous scaffolds as platforms for stem cell expansion. To address the long-lasting challenge of uniform plasma treatment within the micrometre-sized pores of scaffolds, we developed a packed bed plasma immersion ion implantation (PBPI³) technology by which plasma is ignited inside porous materials for homogeneous surface activation. COMSOL Multiphysics simulations support our experimental data and provide insights into the role of electrical field and pressure distribution in plasma ignition. Spatial surface characterisation inside scaffolds demonstrates the homogeneity of PBPI³ activation. The PBPI³ treatment induces radical-containing chemical structures that enable the covalent attachment of biomolecules via a simple, non-toxic, single-step incubation process. We showed that PBPI³-treated scaffolds biofunctionalised with fibroblast growth factor 2 (FGF2) significantly promoted the expansion of MSCs, preserved cell phenotypic expression, and multipotency, while reducing the usage of costly growth factor supplements. This breakthrough PBPI³ technology can be applied to a wide range of 3D polymeric porous scaffolds, paving the way towards developing new biomimetic interfaces for tissue engineering and regenerative medicine.

A simple and robust serum-free media for the proliferation of muscle cells

Cultivated meat production requires an efficient, robust and highly optimized serum-free cell culture media for the needed upscaling of muscle cell expansion. Existing formulations of serum-free media are complex, expensive and have not been optimized for muscle cells. Thus, we undertook this work to develop a simple and robust serum-free media for the proliferation of bovine satellite cells (SCs) through Design of Experiment (DOE) and Response Surface Methodology (RSM) using precise and high-throughput image-based cytometry. Proliferative attributes were investigated with transcriptomics and long-term performance was validated using multiple live assays. Here we formulated a media based on three highly optimized components; FGF2 (2 ng/mL), fetuin (600 µg/mL) and BSA (75 µg/mL) which together with an insulin-transferrin-selenium (1x) supplement, sustained the proliferation of bovine SCs, porcine SCs and murine C2C12 muscle cells. Remarkably, cells cultured in our media named Tri-basal 2.0+ performed better than cell cultured in 10% FBS, with respect to proliferation. Hence, the optimized Tri-basal 2.0+ enhanced serum-free cell attachment and long-term proliferation, providing an alternative solution to the use of FBS in the production of cultivated meat.

Zinc enhances the cell adhesion, migration, and self-renewal potential of human umbilical cord derived mesenchymal stem cells

BACKGROUND

Zinc (Zn) is the second most abundant trace element after Fe, present in the human body. It is frequently reported in association with cell growth and proliferation, and its deficiency is considered to be a major disease contributing factor.

AIM

To determine the effect of Zn on in vitro growth and proliferation of human umbilical cord (hUC)-derived mesenchymal stem cells (MSCs).

METHODS

hUC-MSCs were isolated from human umbilical cord tissue and characterized based on immunocytochemistry, immunophenotyping, and tri-lineage differentiation. The impact of Zn on cytotoxicity and proliferation was determined by MTT and Alamar blue assay. To determine the effect of Zn on population doubling time (PDT), hUC-MSCs were cultured in media with and without Zn for several passages. An in vitro scratch assay was performed to analyze the effect of Zn on the wound healing and migration capability of hUC-MSCs. A cell adhesion assay was used to test the surface adhesiveness of hUC-MSCs. Transcriptional analysis of genes involved in the cell cycle, proliferation, migration, and self-renewal of hUC-MSCs was performed by quantitative real-time polymerase chain reaction. The protein expression of Lin28, a pluripotency marker, was analyzed by immunocytochemistry.

RESULTS

Zn at lower concentrations enhanced the rate of proliferation but at higher concentrations (> 100 µM), showed concentration dependent cytotoxicity in hUC-MSCs. hUC-MSCs treated with Zn exhibited a significantly greater healing and migration rate compared to untreated cells. Zn also increased the cell adhesion rate, and colony forming efficiency (CFE). In addition, Zn upregulated the expression of genes involved in the cell cycle (CDC20, CDK1, CCNA2, CDCA2), proliferation (transforming growth factor β1, GDF5, hypoxia-inducible factor 1α), migration (CXCR4, VCAM1, VEGF-A), and self-renewal (OCT4, SOX2, NANOG) of hUC-MSCs. Expression of Lin28 protein was significantly increased in cells treated with Zn.

CONCLUSION

Our findings suggest that zinc enhances the proliferation rate of hUC-MSCs decreasing the PDT, and maintaining the CFE. Zn also enhances the cell adhesion, migration, and self-renewal of hUC-MSCs. These results highlight the essential role of Zn in cell growth and development.

Proliferative Effect of Aqueous Extract of Sea Cucumber (Holothuria parva) Body Wall on Human Umbilical Cord Mesenchymal Stromal/Stem Cells

Sea cucumber extracts and their bioactive compounds have the potential for stem cell proliferation induction and for their beneficial therapeutic properties. In this study, human umbilical cord mesenchymal stromal/stem cells (hUC-MSCs) were exposed to an aqueous extract of Holothuria parva body walls. Proliferative molecules were detected using gas chromatography-mass spectrometry (GC-MS) analysis in an aqueous extract of H. parva. The aqueous extract concentrations of 5, 10, 20, 40, and 80 µg/mL and 10 and 20 ng/mL of human epidermal growth factor (EGF) as positive controls were treated on hUC-MSCs. MTT, cell count, viability, and cell cycle assays were performed. Using Western blot analysis, the effects of extracts of H. parva and EGF on cell proliferation markers were detected. Computational modeling was done to detect effective proliferative compounds in the aqueous extract of H. parva. A MTT assay showed that the 10, 20, and 40 µg/mL aqueous extract of H. parva had a proliferative effect on hUC-MSCs. The cell count, which was treated with a 20 µg/mL concentration, increased faster and higher than the control group (p < 0.05). This concentration of the extract did not have a significant effect on hUC-MSCs' viability. The cell cycle assay of hUC-MSCs showed that the percentage of cells in the G2 stage of the extract was biologically higher than the control group. Expression of cyclin D1, cyclin D3, cyclin E, HIF-1α, and TERT was increased compared with the control group. Moreover, expression of p21 and PCNA decreased after treating hUC-MSCs with the extract. However, CDC-2/cdk-1 and ERK1/2 had almost the same expression as the control group. The expression of CDK-4 and CDK-6 decreased after treatment. Between the detected compounds, 1-methyl-4-(1-methyl phenyl)-benzene showed better affinity to CDK-4 and p21 than tetradecanoic acid. The H. parva aqueous extract showed proliferative potential on hUC-MSCs.

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Common and rare variants of EGF increase the genetic risk of Alzheimer's disease as revealed by targeted sequencing of growth factors in Han Chinese

Alzheimer's disease (AD) is the most common neurodegenerative disease with high heritability. Growth factors (GFs) might contribute to the development of AD due to their broad effects on neuronal system. We herein aimed to investigate the role of rare and common variants of GFs in genetic susceptibility of AD. We screened 23 GFs in 6324 individuals using targeted sequencing. A rare-variant-based burden test and common-variant-based single-site association analyses were performed to identify AD-associated GF genes and variants. The burden test showed an enrichment of rare missense variants (p = 6.08 × 10^-4) in GF gene-set in AD patients. Among the GFs, EGF showed the strongest signal of enrichment, especially for loss-of-function variants (p = 0.0019). A common variant rs4698800 of EGF showed significant associations with AD risk (p = 3.24 × 10^-5, OR = 1.26). The risk allele of rs4698800 was associated with an increased EGF expression, whereas EGF was indeed upregulated in AD brain. These findings suggested EGF as a novel risk gene for AD.

To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors

Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.

Matricellular protein Tenascin-C enhances mesenchymal stem cell angiogenic and wound healing efficacy under ischemic conditions

Human mesenchymal stem cells/multipotent stromal cells (MSCs) hold great promise in aiding wound healing through their ability to modulate all phases of repair and regeneration, most notably their secretion of pro-regenerative paracrine factors. However, MSC clinical utility is hindered by poor survival rates post-transplantation due to the harsh microenvironment in injured tissue. Previous work has shown that the matricellular protein Tenascin-C (TNC) provides survival signaling to MSCs via the epidermal growth factor receptor by restricting its activation at the plasma membrane, resulting in enhanced prosurvival signals. Herein, we investigate how TNC influences MSC survival and MSC-mediated promotion of the wound healing process. This study examined the survival and angiogenic potential of MSCs cultured on TNC-coated surfaces under ischemic duress in vitro. We also assessed the angiogenic and wound healing outcomes of MSC + TNC in vivo using a CXCR3-/- mouse model that exhibits a delayed healing phenotype within the tissue replacement phase of repair. We found that MSCs in the presence of TNC exhibit higher levels of angiogenic-promoting processes, collagen maturation, and an overall better wound healing outcome than MSCs administered alone. This was seen in vitro in terms of enhanced tube formation. In vivo, the MSCs in the presence of TNC stabilized with a coacervate delivery system resulted in more regenerative wounds with accelerated maturation of the dermis. These findings suggest the coupling of TNC to MSCs as a promising tool for future MSC-ECM combinatorial therapies for wound healing applications.

The Role of Transforming Growth Factor Beta in Joint Homeostasis and Cartilage Regeneration

Transforming growth factor-beta (TGF-β) is an important regulator of joint homeostasis, of which dysregulation is closely associated with the development of osteoarthritis (OA). In normal conditions, its biological functions in a joint environment are joint protective, but it can be dramatically altered in different contexts, making its therapeutic application a challenge. However, with the deeper insights into the TGF-β functions, it has been proven that TGF-β augments cartilage regeneration by chondrocytes, and differentiates both the precursor cells of chondrocytes and stem cells into cartilage-generating chondrocytes. Following documentation of the therapeutic efficacy of chondrocytes augmented by TGF-β in the last decade, there is an ongoing phase III clinical trial examining the therapeutic efficacy of a mixture of allogeneic chondrocytes and TGF-β-overexpressing cells. To prepare cartilage-restoring chondrocytes from induced pluripotent stem cells (iPSCs), the stem cells are differentiated mainly using TGF-β with some other growth factors. Of note, clinical trials evaluating the therapeutic efficacy of iPSCs for OA are scheduled this year. Mesenchymal stromal stem cells (MSCs) have inherent limitations in that they differentiate into the osteochondral pathway, resulting in the production of poor-quality cartilage. Despite the established essential role of TGF-β in chondrogenic differentiation of MSCs, whether the coordinated use of TGF-β in MSC-based therapy for degenerated cartilage is effective is unknown. We herein reviewed the general characteristics and mechanism of action of TGF-β in a joint environment. Furthermore, we discussed the core interaction of TGF-β with principal cells of OA cell-based therapies, the chondrocytes, MSCs, and iPSCs. Impact Statement Transforming growth factor-beta (TGF-β) has been widely used as a core regulator to improve or formulate therapeutic regenerative cells for degenerative joints. It differentiates stem cells into chondrocytes and improves the chondrogenic potential of differentiated chondrocytes. Herein, we discussed the overall characteristics of TGF-β and reviewed the comprehension and utilization of TGF-β in cell-based therapy for degenerative joint disease.

Current Status of Mesenchymal Stem/Stromal Cells for Treatment of Neurological Diseases

Neurological disorders include a wide spectrum of clinical conditions affecting the central and peripheral nervous systems. For these conditions, which affect hundreds of millions of people worldwide, generally limited or no treatments are available, and cell-based therapies have been intensively investigated in preclinical and clinical studies. Among the available cell types, mesenchymal stem/stromal cells (MSCs) have been widely studied but as yet no cell-based treatment exists for neurological disease. We review current knowledge of the therapeutic potential of MSC-based therapies for neurological diseases, as well as possible mechanisms of action that may be explored to hasten the development of new and effective treatments. We also discuss the challenges for culture conditions, quality control, and the development of potency tests, aiming to generate more efficient cell therapy products for neurological disorders.

Heterogeneity of In Vitro Expanded Mesenchymal Stromal Cells and Strategies to Improve Their Therapeutic Actions

Beneficial properties of mesenchymal stromal cells (MSCs) have prompted their use in preclinical and clinical research. Accumulating evidence has been provided for the therapeutic effects of MSCs in several pathologies, including neurodegenerative diseases, myocardial infarction, skin problems, liver disorders and cancer, among others. Although MSCs are found in multiple tissues, the number of MSCs is low, making in vitro expansion a required step before MSC application. However, culture-expanded MSCs exhibit notable differences in terms of cell morphology, physiology and function, which decisively contribute to MSC heterogeneity. The changes induced in MSCs during in vitro expansion may account for the variability in the results obtained in different MSC-based therapy studies, including those using MSCs as living drug delivery systems. This review dissects the different changes that occur in culture-expanded MSCs and how these modifications alter their therapeutic properties after transplantation. Furthermore, we discuss the current strategies developed to improve the beneficial effects of MSCs for successful clinical implementation, as well as potential therapeutic alternatives.

Principles for the design of multicellular engineered living systems

Remarkable progress in bioengineering over the past two decades has enabled the formulation of fundamental design principles for a variety of medical and non-medical applications. These advancements have laid the foundation for building multicellular engineered living systems (M-CELS) from biological parts, forming functional modules integrated into living machines. These cognizant design principles for living systems encompass novel genetic circuit manipulation, self-assembly, cell-cell/matrix communication, and artificial tissues/organs enabled through systems biology, bioinformatics, computational biology, genetic engineering, and microfluidics. Here, we introduce design principles and a blueprint for forward production of robust and standardized M-CELS, which may undergo variable reiterations through the classic design-build-test-debug cycle. This Review provides practical and theoretical frameworks to forward-design, control, and optimize novel M-CELS. Potential applications include biopharmaceuticals, bioreactor factories, biofuels, environmental bioremediation, cellular computing, biohybrid digital technology, and experimental investigations into mechanisms of multicellular organisms normally hidden inside the "black box" of living cells.

Peptide-Modified Nano-Bioactive Glass for Targeted Immobilization of Native VEGF

A limiting factor in large bone defect regeneration is the slow and disorganized formation of a functional vascular network in the defect area, often resulting in delayed healing or implant failure. To overcome this, strategies that induce angiogenic processes should be combined with potent bone graft substitutes in new bone regeneration approaches. To this end, we describe a unique approach to immobilize the pro-angiogenic growth factor VEGF₁₆₅ in its native state on the surface of nanosized bioactive glass particles (nBGs) via a binding peptide (PR1P). We demonstrate that covalent coupling of the peptide to amine functional groups grafted on the nBG surface allows immobilization of VEGF with high efficiency and specificity. The amount of coupled peptide could be controlled by varying amine density, which eventually allows tailoring the amount of bound VEGF within a physiologically effective range. In vitro analysis of endothelial cell tube formation in response to VEGF-carrying nBG confirmed that the biological activity of VEGF is not compromised by the immobilization. Instead, comparable angiogenic stimulation was found for lower doses of immobilized VEGF compared to exogenously added VEGF. The described system, for the first time, employs a binding peptide for growth factor immobilization on bioactive glass nanoparticles and represents a promising strategy to overcome the problem of insufficient neovascularization in large bone defect regeneration.

Substance P modulates BMSCs migration for tissue repair through NK-1R/CXCR4/p-Akt signal activation

BACKGROUND

The migration of bone marrow-derived mesenchymal stem cells (BMSCs) to the wound site played an important role in tissue repair. Substance P (SP) has been studied and reported to be involved in tissue repair by promoting the growth of endothelial cells and the migration of BMSCs. However, the complicated process and the molecular mechanisms were not fully understood. Thus, we aimed to investigate the effect of SP-induced BMSCs migration on tissue repair and its possible mechanism.

METHODS AND RESULTS

Western blot and q-PCR assay revealed that SP could induce the BMSCs migration through overexpression of CXCR4 and upregulation of Akt phosphorylation. And the upregulation was related to the activation of neurokinin-1 receptor (NK-1R). Besides, we found that the increased phosphorylation Akt caused by SP could be canceled by the inhibition of CXCR4 both in vitro and in vivo. Furthermore, a skin-injury animal model was established and used to observe the tissue repair process. Results showed that SP could accelerate wound closure, gain more granulation tissue accumulation, and more collagen deposition through the promotion of angiogenesis and induction of the BMSCs migration to the wound site. And these effects could be impaired by inhibition of CXCR4 and p-Akt.

CONCLUSIONS

Our results suggested that SP promoted tissue repair through BMSCs migration via upregulation of CXCR4 and p-Akt. The expression of CXCR4 and p-Akt were regulated by NK-1R activation. These findings add more evidence in understanding the mechanisms of SP-induced BMSCs migration and highlight the potential for clinical implementation of SP in tissue repair.

A poly(ethylene glycol) three-dimensional bone marrow hydrogel

Three-dimensional (3D) hydrogels made from synthetic polymers have emerged as in vitro cell culture platforms capable of representing the extracellular geometry, modulus, and water content of tissues in a tunable fashion. Hydrogels made from these otherwise non-bioactive polymers can be decorated with short peptides derived from proteins naturally found in tissues to support cell viability and direct phenotype. We identified two key limitations that limit the ability of this class of materials to recapitulate real tissue. First, these environments typically display between 1 and 3 bioactive peptides, which vastly underrepresents the diversity of proteins found in the extracellular matrix (ECM) of real tissues. Second, peptides chosen are ubiquitous in ECM and not derived from proteins found in specific tissues, per se. To overcome this critical limitation in hydrogel design and functionality, we developed an approach to incorporate the complex and specific protein signature of bone marrow into a poly (ethylene glycol) (PEG) hydrogel. This bone marrow hydrogel mimics the elasticity of marrow and has 20 bone marrow-specific and cell-instructive peptides. We propose this tissue-centric approach as the next generation of 3D hydrogel design for applications in tissue engineering and beyond.

Conditioned Medium from Bone Marrow Mesenchymal Stem Cells Restored Oxidative Stress-Related Impaired Osteogenic Differentiation

Oxidative stress from high levels of intracellular reactive oxygen species (ROS) has been linked to various bone diseases. Previous studies indicate that mesenchymal stem cells (MSC) secrete bioactive factors (conditioned medium (MSC-CM)) that have antioxidant effects. However, the antioxidant role of MSC-CM on osteogenesis has not been fully studied. We aimed to identify antioxidant proteins in MSC-CM using mass spectrometry-based proteomics and to explore their effects on osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSC) exposed to oxidative stress induced by hydrogen peroxide (H₂O₂). Our analysis revealed that MSC-CM is comprised of antioxidant proteins that are involved in several biological processes, including negative regulation of apoptosis and positive regulation of cell proliferation. Then, hBMSC exposed to H₂O₂ were treated with MSC-CM, and the effects on their osteogenic differentiation were evaluated. MSC-CM restored H₂O₂-induced damage to hBMSC by increasing the antioxidant enzyme-SOD production and the mRNA expression level of the anti-apoptotic BCL-2. A decrease in ROS production and cellular apoptosis was also shown. MSC-CM also modulated mRNA expression levels of osteogenesis-related genes, runt-related transcription factor 2, collagen type I, bone morphogenic protein 2, and osteopontin. Furthermore, collagen type I protein secretion, alkaline phosphatase activity, and in vitro mineralization were increased. These results indicate that MSC-CM contains several proteins with antioxidant and anti-apoptotic properties that restored the impaired hBMSC osteogenic differentiation associated with oxidative stress.

Effect of Combined Leukocyte-Poor Platelet-Rich Plasma and Hyaluronic Acid on Bone Marrow-Derived Mesenchymal Stem Cell and Chondrocyte Metabolism

OBJECTIVE

Given the potential applications of combined biologics, the authors sought to evaluate the in vitro effect of combined platelet-rich plasma (PRP) and hyaluronic acid (HA) on cellular metabolism.

DESIGN

Bone marrow-derived mesenchymal stem cells (BMSCs) and chondrocytes were obtained from the femurs of Sprague-Dawley rats. An inflammatory model was created by adding 10 ng/mL interleukin-1-beta to culture media. Non-crosslinked high-molecular-weight HA, activated-PRP (aPRP), and unactivated-PRP (uPRP) were tested. Cellular proliferation and gene expression were measured at 1 week. Genes of interest included aggrecan, matrix metalloproteinase (MMP)-9, and MMP-13.

RESULTS

Combined uPRP-HA was associated with a significant increase in chondrocyte and BMSC proliferation at numerous preparations. There was a trend of increased chondrocyte aggrecan expression with combined PRP-HA. The greatest and only significant decrease in BMSC MMP-9 expression was observed with combined PRP-HA. While a significant reduction of BMSC MMP-13 expression was seen with PRP and HA-alone, a greater reduction was observed with PRP-HA. MMP-9 chondrocyte expression was significantly reduced in cells treated with PRP-HA. PRP-alone and HA-alone at identical concentrations did not result in a significant reduction. The greatest reduction of MMP-13 chondrocyte expression was observed in chondrocytes plus combined PRP-HA.

CONCLUSIONS

We demonstrated a statistically significant increase in BMSC and chondrocyte proliferation and decreased expression of catabolic enzymes with combined PRP-HA. These results demonstrate the additive in vitro effect of combined PRP-HA to stimulate cellular growth, restore components of the articular extracellular matrix, and reduce inflammation.

Transplant of Autologous Mesenchymal Stem Cells Halts Fatty Atrophy of Detached Rotator Cuff Muscle After Tendon Repair: Molecular, Microscopic, and Macroscopic Results From an Ovine Model

BACKGROUND

The injection of mesenchymal stem cells (MSCs) mitigates fat accumulation in released rotator cuff muscle after tendon repair in rodents.

PURPOSE

To investigate whether the injection of autologous MSCs halts muscle-to-fat conversion after tendon repair in a large animal model for rotator cuff tendon release via regional effects on extracellular fat tissue and muscle fiber regeneration.

STUDY DESIGN

Controlled laboratory study.

METHODS

Infraspinatus (ISP) muscles of the right shoulder of Swiss Alpine sheep (n = 14) were released by osteotomy and reattached 16 weeks later without (group T; n = 6) or with (group T-MSC; n = 8) electropulse-assisted injection of 0.9 Mio fluorescently labeled MSCs as microtissues with media in demarcated regions; animals were allowed 6 weeks of recovery. ISP volume and composition were documented with computed tomography and magnetic resonance imaging. Area percentages of muscle fiber types, fat, extracellular ground substance, and fluorescence-positive tissue; mean cross-sectional area (MCSA) of muscle fibers; and expression of myogenic (myogenin), regeneration (tenascin-C), and adipogenic markers (peroxisome proliferator-activated receptor gamma [PPARG2]) were quantified in injected and noninjected regions after recovery.

RESULTS

At 16 weeks after tendon release, the ISP volume was reduced and the fat fraction of ISP muscle was increased in group T (137 vs 185 mL; 49% vs 7%) and group T-MSC (130 vs 166 mL; 53% vs 10%). In group T-MSC versus group T, changes during recovery after tendon reattachment were abrogated for fat-free mass (-5% vs -29%, respectively; P = .018) and fat fraction (+1% vs +24%, respectively; P = .009%). The area percentage of fat was lower (9% vs 20%; P = .018) and the percentage of the extracellular ground substance was higher (26% vs 20%; P = .007) in the noninjected ISP region for group T-MSC versus group T, respectively. Regionally, MCS injection increased tenascin-C levels (+59%) and the water fraction, maintaining the reduced PPARG2 levels but not the 29% increased fiber MCSA, with media injection.

CONCLUSION

In a sheep model, injection of autologous MSCs in degenerated rotator cuff muscle halted muscle-to-fat conversion during recovery from tendon repair by preserving fat-free mass in association with extracellular reactions and stopping adjuvant-induced muscle fiber hypertrophy.

CLINICAL RELEVANCE

A relatively small dose of MSCs is therapeutically effective to halt fatty atrophy in a large animal model.

Potential Role of Growth Factors Controlled Release in Achieving Enhanced Neuronal Trans-differentiation from Mesenchymal Stem Cells for Neural Tissue Repair and Regeneration

With an increase in the incidence of neurodegenerative diseases, a need to replace incapable conventional methods has arisen. To overcome this burden, stem cells therapy has emerged as an efficient treatment option. Endeavours to accomplish this have paved the path to neural regeneration through efficient neuronal transdifferentiation. Despite their potential, the use of stem cells still entails several limitations, such as low differentiation efficiency and difficulties in guiding differentiation. The process of neural differentiation through the stem cells is achieved through the use of chemical inducers or growth factors and their direct introduction reduces their bioavailability in the system. To address these limitations, neural regeneration ventures require growth factors to be effectively implemented on stem cells in order to produce functional neuronal precursor cells. An efficient technique to achieve it is through the delivery of growth factors via microcarriers for their sustained release. It ensures the presence of commensurable concentration even at later stages of neuronal transdifferentiation. Nanofibers and nanoparticles, along with liposomes and such, have been used to implement this. The interaction between such carriers and the growth factors is mainly electrostatic. Such interaction enables them to form a stable assembly through immobilisation of the growth factor either onto their surfaces or within the core of their structures. The rate of sustained release depends upon the release kinetics associated with the polymeric structure employed and its interaction with the encapsulated growth factor. The sustained release ensures that the stem cells immerse under the effect of the growth factors for a prolonged period, ultimately aiding in the formation of cells showing ample characteristics of neuron precursors. This review analyses the various carriers that have been employed for the release of growth factors in an orderly fashion and their constituents, along with the advantages and the limitations they pose in delivering the growth factors for facilitating the process of neuronal transdifferentiation.

Prognostic association of starvation-induced gene expression in head and neck cancer

Autophagy-related genes (ARGs) have been implicated in the initiation and progression of malignant tumor promotion. To investigate the dynamics of expression of genes, including ARGs, head and neck squamous cell carcinoma (HNSCC) cells were placed under serum-free conditions to induce growth retardation and autophagy, and these starved cells were subjected to transcriptome analysis. Among the 21 starvation-induced genes (SIGs) located in the autophagy, cell proliferation, and survival signaling pathways, we identified SIGs that showed prominent up-regulation or down-regulation in vitro. These included AGR2, BST2, CALR, CD22, DDIT3, FOXA2, HSPA5, PIWIL4, PYCR1, SGK3, and TRIB3. The Cancer Genome Atlas (TCGA) database of HNSCC patients was used to examine the expression of up-regulated genes, and CALR, HSPA5, and TRIB3 were found to be highly expressed relative to solid normal tissue in cancer and the survival rate was reduced in patients with high expression. Protein-protein interaction analysis demonstrated the formation of a dense network of these genes. Cox regression analysis revealed that high expression of CALR, HSPA5, and TRIB3 was associated with poor prognosis in patients with TCGA-HNSCC. Therefore, these SIGs up-regulated under serum starvation may be molecular prognostic markers in HNSCC patients.

A Focus on "Bio" in Bio-Nanoscience: The Impact of Biological Factors on Nanomaterial Interactions

Bio-nanoscience research encompasses studies on the interactions of nanomaterials with biological structures or what is commonly referred to as the biointerface. Fundamental studies on the influence of nanomaterial properties, including size, shape, composition, and charge, on the interaction with the biointerface have been central in bio-nanoscience to assess nanomaterial efficacy and safety for a range of biomedical applications. However, the state of the cells, tissues, or biological models can also influence the behavior of nanomaterials at the biointerface and their intracellular processing. Focusing on the "bio" in bio-nano, this review discusses the impact of biological properties at the cellular, tissue, and whole organism level that influences nanomaterial behavior, including cell type, cell cycle, tumor physiology, and disease states. Understanding how the biological factors can be addressed or exploited to enhance nanomaterial accumulation and uptake can guide the design of better and suitable models to improve the outcomes of materials in nanomedicine.

Cranial Suture Mesenchymal Stem Cells: Insights and Advances

The cranial bones constitute the protective structures of the skull, which surround and protect the brain. Due to the limited repair capacity, the reconstruction and regeneration of skull defects are considered as an unmet clinical need and challenge. Previously, it has been proposed that the periosteum and dura mater provide reparative progenitors for cranial bones homeostasis and injury repair. In addition, it has also been speculated that the cranial mesenchymal stem cells reside in the perivascular niche of the diploe, namely, the soft spongy cancellous bone between the interior and exterior layers of cortical bone of the skull, which resembles the skeletal stem cells’ distribution pattern of the long bone within the bone marrow. Not until recent years have several studies unraveled and validated that the major mesenchymal stem cell population of the cranial region is primarily located within the suture mesenchyme of the skull, and hence, they are termed suture mesenchymal stem cells (SuSCs). Here, we summarized the characteristics of SuSCs, this newly discovered stem cell population of cranial bones, including the temporospatial distribution pattern, self-renewal, and multipotent properties, contribution to injury repair, as well as the signaling pathways and molecular mechanisms associated with the regulation of SuSCs.

Adipose-Derived Stem Cells Based on Electrospun Biomimetic Scaffold Mediated Endothelial Differentiation Facilitating Regeneration and Repair of Abdominal Wall Defects via HIF-1α/VEGF Pathway

Application of synthetic or biological meshes is the main therapy for the repair and reconstruction of abdominal wall defects, a common disease in surgery. Currently, no ideal materials are available, and there is an urgent need to find appropriate ones to satisfy clinical needs. Electrospun scaffolds have drawn attention in soft tissue reconstruction. In this study, we developed a novel method to fabricate a composite electrospun scaffold using a thermoresponsive hydrogel, poly (N-isopropylacrylamide)-block-poly (ethylene glycol), and a biodegradable polymer, polylactic acid (PLA). This scaffold provided not only a high surface area/volume ratio and a three-dimensional fibrous matrix but also high biocompatibility and sufficient mechanical strength, and could simulate the native extracellular matrix and accelerate cell adhesion and proliferation. Furthermore, rat adipose-derived stem cells (ADSCs) were seeded in the composite electrospun scaffold to enhance the defect repair and regeneration by directionally inducing ADSCs into endothelial cells. In addition, we found early vascularization in the process was regulated by the hypoxia inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway. In our study, overexpression of HIF-1α/VEGF in ADSCs using a lentivirus system promoted early vascularization in the electrospun scaffolds. Overall, we expect our composite biomimetic scaffold method will be applicable and useful in abdominal wall defect regeneration and repair in the future.

Hydrogels for Large-Scale Expansion of Stem Cells

Stem cells demonstrate considerable promise for various preclinical and clinical applications, including drug screening, disease treatments, and regenerative medicine. Producing high-quality and large amounts of stem cells is in demand for these applications. Despite challenges, as hydrogel-based cell culture technology has developed, tremendous progress has been made in stem cell expansion and directed differentiation. Hydrogels are soft materials with abundant water. Many hydrogel properties, including biodegradability, mechanical strength, and porosity, have been shown to play essential roles in regulating stem cell proliferation and differentiation. The biochemical and physical properties of hydrogels can be specifically tailored to mimic the native microenvironment that various stem cells reside in vivo. A few hydrogel-based systems have been developed for successful stem cell cultures and expansion in vitro. In this review, we summarize various types of hydrogels that have been designed to effectively enhance the proliferation of hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs), respectively. According to each stem cell type's preference, we also discuss strategies for fabricating hydrogels with biochemical and mechanical cues and other characteristics representing microenvironments of stem cells in vivo. STATEMENT OF SIGNIFICANCE: In this review article we summarize current progress on the construction of hydrogel systems for the culture and expansion of various stem cells, including hematopoietic stem cells (HSCs), mesenchymal stem/stromal cells (MSCs), and pluripotent stem cells (PSCs). The Significance includes: (1) Provide detailed discussion on the stem cell niches that should be considered for stem cell in vitro expansion. (2) Summarize various strategies to construct hydrogels that can largely recapture the microenvironment of native stem cells. (3) Suggest a few future directions that can be implemented to improve current in vitro stem cell expansion systems.

The Role of BMP Signaling in Osteoclast Regulation

The osteogenic effects of Bone Morphogenetic Proteins (BMPs) were delineated in 1965 when Urist et al. showed that BMPs could induce ectopic bone formation. In subsequent decades, the effects of BMPs on bone formation and maintenance were established. BMPs induce proliferation in osteoprogenitor cells and increase mineralization activity in osteoblasts. The role of BMPs in bone homeostasis and repair led to the approval of BMP2 by the Federal Drug Administration (FDA) for anterior lumbar interbody fusion (ALIF) to increase the bone formation in the treated area. However, the use of BMP2 for treatment of degenerative bone diseases such as osteoporosis is still uncertain as patients treated with BMP2 results in the stimulation of not only osteoblast mineralization, but also osteoclast absorption, leading to early bone graft subsidence. The increase in absorption activity is the result of direct stimulation of osteoclasts by BMP2 working synergistically with the RANK signaling pathway. The dual effect of BMPs on bone resorption and mineralization highlights the essential role of BMP-signaling in bone homeostasis, making it a putative therapeutic target for diseases like osteoporosis. Before the BMP pathway can be utilized in the treatment of osteoporosis a better understanding of how BMP-signaling regulates osteoclasts must be established.

The regenerative effect of different growth factors and platelet lysate on meniscus cells and mesenchymal stromal cells and proof of concept with a functionalized meniscus implant

Meniscus regeneration could be enhanced by targeting meniscus cells and mesenchymal stromal cells (MSCs) with the right growth factors. Combining these growth factors with the Collagen Meniscus Implant (CMI®) could accelerate cell ingrowth and tissue formation in the implant and thereby improve clinical outcomes. Using a transwell migration assay and a micro-wound assay, the effect of insulin-like growth factor-1, platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), transforming growth factor beta 1 (TGF-β1), fibroblast growth factor, and platelet lysate (PL) on migration and proliferation of meniscus cells and MSCs was assessed. The formation of extracellular matrix under influence of the above-mentioned growth factors was assessed after 28 days of culture of both MSCs and meniscus cells. As a proof of concept, the CMI® was functionalized with a VEGF binding peptide and coated with platelet-rich plasma (PRP) for clinical application. Our results demonstrate that PDGF, TGF-β1, and PL stimulate migration, proliferation, and/or extracellular matrix production of meniscus cells and MSCs. Additionally, the CMI® was successfully functionalized with a VEGF binding peptide and PRP which increased migration of meniscus cell and MSC into the implant. This study demonstrates proof of concept of functionalizing the CMI® with growth factor binding peptides. A CMI® functionalized with the right growth factors holds great potential for meniscus replacement after partial meniscectomy.

Cell-cell and cell-substratum contacts in the regulation of MAPK and Akt signalling: Importance in therapy, biopharmacy and bioproduction

The use of cultured cells as a tool for research, precision medicine, biopharmacy, and biomanufacturing is constantly increasing. In parallel, the role of cell-cell and cell-substratum contacts in cell functioning is increasingly validated. Adhesion signalling plays a key role here. The activity of cell fate-regulating signalling molecules is an important factor in determining cell behaviour, as well as their response to treatment, depending on cell phenotypic status and location in the body. Three cellular state models (adherent, single cells in suspension, and aggregated cells) were compared for cell signalling, including focal adhesion (FAK), mitogen-activated (MAPK), as well as Akt protein kinases, and transcription factor cJun, by using lung adenocarcinoma A549, muscle-derived stem Myo, as well as primary lung cancer cell lines. Survival of both A549 and Myo cells was dependent on kinases Akt and ERK in detached conditions. Intercellular contacts in aggregates promoted activation of Akt and ERK, and cell survival. Loss of contacts with the substrate increased phosphorylation of MAP kinases JNK and p38, while decreased Akt phosphorylation by processes involving FAK. Unexpectedly, detachment increased phosphorylation of antiapoptotic kinase ERK in A549, while in Myo stem cells ERK phosphorylation was downregulated. JNK target transcription factor cJun protein level was markedly diminished by contacts between cells possibly involving mechanism of proteasomal degradation. Furthermore, studies revealed the opposite dependence of molecules of the same signalling pathway - phospho-cJun and phospho-JNK - on cell culture density. Differences in ERK activation under detachment conditions indicate that targeting of prosurvival kinases during anoikis should be different in different cells. Moreover, the outcome of JNK activation in cells may depend on the amount of cJun, which is determined by cell-cell contacts.

Cardiac Differentiation of Mesenchymal Stem Cells: Impact of Biological and Chemical Inducers

Cardiovascular disorders (CVDs) are the leading cause of global death, widely occurs due to irreparable loss of the functional cardiomyocytes. Stem cell-based therapeutic approaches, particularly the use of Mesenchymal Stem Cells (MSCs) is an emerging strategy to regenerate myocardium and thereby improving the cardiac function after myocardial infarction (MI). Most of the current approaches often employ the use of various biological and chemical factors as cues to trigger and modulate the differentiation of MSCs into the cardiac lineage. However, the recent advanced methods of using specific epigenetic modifiers and exosomes to manipulate the epigenome and molecular pathways of MSCs to modify the cardiac gene expression yield better profiled cardiomyocyte like cells in vitro. Hitherto, the role of cardiac specific inducers triggering cardiac differentiation at the cellular and molecular level is not well understood. Therefore, the current review highlights the impact and recent trends in employing biological and chemical inducers on cardiac differentiation of MSCs. Thereby, deciphering the interactions between the cellular microenvironment and the cardiac inducers will help us to understand cardiomyogenesis of MSCs. Additionally, the review also provides an insight on skeptical roles of the cell free biological factors and extracellular scaffold assisted mode for manipulation of native and transplanted stem cells towards translational cardiac research.

3D cell sheet structure augments mesenchymal stem cell cytokine production

Mesenchymal stem cells (MSCs) secrete paracrine factors that play crucial roles during tissue regeneration. An increasing body of evidence suggests that this paracrine function is enhanced by MSC cultivation in three-dimensional (3D) tissue-like microenvironments. Toward this end, this study explored scaffold-free cell sheet technology as a new 3D platform. MSCs cultivated on temperature-responsive culture dishes to a confluent 2D monolayer were harvested by temperature reduction from 37 to 20 °C that induces a surface wettability transition from hydrophobic to hydrophilic. Release of culture-adherent tension induced spontaneous cell sheet contraction, reducing the diameter 2.4-fold, and increasing the thickness 8.0-fold to render a 3D tissue-like construct with a 36% increase in tissue volume. This 2D-to-3D transition reorganized MSC actin cytoskeleton from aligned to multidirectional, corresponding to a cell morphological change from elongated in 2D monolayers to rounded in 3D cell sheets. 3D culture increased MSC gene expression of cell interaction proteins, β-catenin, integrin β1, and connexin 43, and of pro-tissue regenerative cytokines, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and interleukin-10 (IL-10), and increased VEGF secretion per MSC 2.1-fold relative to 2D cultures. Together, these findings demonstrate that MSC therapeutic potency can be enhanced by 3D cell sheet tissue structure.

Towards Physiologic Culture Approaches to Improve Standard Cultivation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are of great interest for their use in cell-based therapies due to their multipotent differentiation and immunomodulatory capacities. In consequence of limited numbers following their isolation from the donor tissue, MSCs require extensive expansion performed in traditional 2D cell culture setups to reach adequate amounts for therapeutic use. However, prolonged culture of MSCs in vitro has been shown to decrease their differentiation potential and alter their immunomodulatory properties. For that reason, preservation of these physiological characteristics of MSCs throughout their in vitro culture is essential for improving the efficiency of therapeutic and in vitro modeling applications. With this objective in mind, many studies already investigated certain parameters for enhancing current standard MSC culture protocols with regard to the effects of specific culture media components or culture conditions. Although there is a lot of diversity in the final therapeutic uses of the cells, the primary stage of standard isolation and expansion is imperative. Therefore, we want to review on approaches for optimizing standard MSC culture protocols during this essential primary step of in vitro expansion. The reviewed studies investigate and suggest improvements focused on culture media components (amino acids, ascorbic acid, glucose level, growth factors, lipids, platelet lysate, trace elements, serum, and xenogeneic components) as well as culture conditions and processes (hypoxia, cell seeding, and dissociation during passaging), in order to preserve the MSC phenotype and functionality during the primary phase of in vitro culture.

Biophysical and Biochemical Cues of Biomaterials Guide Mesenchymal Stem Cell Behaviors

Mesenchymal stem cells (MSCs) have been widely used in the fields of tissue engineering and regenerative medicine due to their self-renewal capabilities and multipotential differentiation assurance. However, capitalizing on specific factors to precisely guide MSC behaviors is the cornerstone of biomedical applications. Fortunately, several key biophysical and biochemical cues of biomaterials that can synergistically regulate cell behavior have paved the way for the development of cell-instructive biomaterials that serve as delivery vehicles for promoting MSC application prospects. Therefore, the identification of these cues in guiding MSC behavior, including cell migration, proliferation, and differentiation, may be of particular importance for better clinical performance. This review focuses on providing a comprehensive and systematic understanding of biophysical and biochemical cues, as well as the strategic engineering of these signals in current scaffold designs, and we believe that integrating biophysical and biochemical cues in next-generation biomaterials would potentially help functionally regulate MSCs for diverse applications in regenerative medicine and cell therapy in the future.

In Vitro Culture Expansion Shifts the Immune Phenotype of Human Adipose-Derived Mesenchymal Stem Cells

Human mesenchymal stem or stromal cells (hMSCs) are known for their potential in regenerative medicine due to their differentiation abilities, secretion of trophic factors, and regulation of immune responses in damaged tissues. Due to the limited quantity of hMSCs typically isolated from bone marrow, other tissue sources, such as adipose tissue-derived mesenchymal stem cells (hASCs), are considered a promising alternative. However, differences have been observed for hASCs in the context of metabolic characteristics and response to in vitro culture stress compared to bone marrow derived hMSCs (BM-hMSCs). In particular, the relationship between metabolic homeostasis and stem cell functions, especially the immune phenotype and immunomodulation of hASCs, remains unknown. This study thoroughly assessed the changes in metabolism, redox cycles, and immune phenotype of hASCs during in vitro expansion. In contrast to BM-hMSCs, hASCs did not respond to culture stress significantly during expansion as limited cellular senescence was observed. Notably, hASCs exhibited the increased secretion of pro-inflammatory cytokines and the decreased secretion of anti-inflammatory cytokines after extended culture expansion. The NAD+/NADH redox cycle and other metabolic characteristics associated with aging were relatively stable, indicating that hASC functional decline may be regulated through an alternative mechanism rather than NAD+/Sirtuin aging pathways as observed in BM-hMSCs. Furthermore, transcriptome analysis by mRNA-sequencing revealed the upregulation of genes for pro-inflammatory cytokines/chemokines and the downregulation of genes for anti-inflammatory cytokines for hASCs at high passage. Proteomics analysis indicated key pathways (e.g., tRNA charging, EIF2 signaling, protein ubiquitination pathway) that may be associated with the immune phenotype shift of hASCs. Together, this study advances our understanding of the metabolism and senescence of hASCs and may offer vital insights for the biomanufacturing of hASCs for clinical use.

Partial hepatectomy enhances the growth of CC531 rat colorectal cancer cells both in vitro and in vivo

Partial hepatectomy (PHx) is the gold standard for the treatment of colorectal cancer liver metastases. However, after removing a substantial amount of hepatic tissue, growth factors are released to induce liver regeneration, which may promote the proliferation of liver micrometastases or circulating tumour cells still present in the patient. The aim of this study is to assess the effect of PHx on the growth of liver metastases induced by intrasplenic cell inoculation as well as on in vitro proliferation of the same cancer cell line. Liver tumours were induced in 18 WAG/RijHsd male rats, by seeding 250,000 syngeneic colorectal cancer cells (CC531) into the spleen. The left lateral lobe of the liver was mobilized and in half of the animals it was removed to achieve a 40% hepatectomy. Twenty-eight days after tumour induction, the animals were sacrificed and the liver was removed and sliced to assess the relative tumour surface area (RTSA%). CC531 cells were cultured in presence of foetal calf serum, non-hepatectomised (NRS) or hepatectomized rat serum (HRS), and their proliferation rate at 24, 48, and 72 h was measured. RTSA% was significantly higher in animals which had undergone PHx than in the controls (non-hepatectomised) (46.98 ± 8.76% vs. 18.73 ± 5.65%; p < 0.05). Analysing each lobe separately, this difference in favour of hepatectomized animals was relevant and statistically significant in the paramedian and caudate lobes. But in the right lobe the difference was scarce and not significant. In vitro, 2.5% HRS achieved stronger proliferative rates than the control cultures (10% FCS) or their equivalent of NRS. In this experimental model, a parallelism has been shown between the effect of PHx on the growth of colorectal cancer cells in the liver and the effect of the serum on those cells in vitro.

Culturing at Low Cell Density Delays Cellular Senescence of Human Bone Marrow-Derived Mesenchymal Stem Cells in Long-Term Cultures

Background and Objectives

Mesenchymal stem cells (MSCs) have immense therapeutic potential for treating intractable and immune diseases. They also have applications in regenerative medicine in which distinct treatments do not exist. Thus, MSCs are gaining attention as important raw materials in the field of cell therapy. Importantly, the number of MSCs in the bone marrow is limited and they are present only in small quantities. Therefore, mass production of MSCs through long-term culture is necessary to use them in cell therapy. However, MSCs undergo cellular senescence through repeated passages during mass production. In this study, we explored methods to prolong the limited lifetime of MSCs by culturing them with different seeding densities.

Methods and Results

We observed that in long-term cultures, low-density (LD, 50 cells/cm²) MSCs showed higher population doubling level, leading to greater fold increase, than high-density (HD, 4,000 cells/cm²) MSCs. LD-MSCs suppressed the expression of aging-related genes. We also showed that reactive oxygen species (ROS) were decreased in LD-MSCs compared to that in HD-MSCs. Further, proliferation potential increased when ROS were inhibited in HD-MSCs.

Conclusions

The results in this study suggest that MSC senescence can be delayed and that life span can be extended by controlling cell density in vitro. These results can be used as important data for the mass production of stem cell therapeutic products.

Platelet lysate: a promising candidate in regenerative medicine

Human platelet lysate has attracted much interest from many researchers as it is growth-factor rich for cell expansion, which is employed as a new therapeutic strategy. Not only are human platelet lysates used for cell therapy, but they are also used for the completion of basal media in mesenchymal stem cell cultures. Due to the presence of a large number of growth factors, platelet lysates have potential roles in wound healing, treatment of ocular graft-versus-host disease, osteoarthritis, Parkinson's disease, tendon regeneration, infertility, androgenetic alopecia, nerve repair and regenerative tissue, such as bone regeneration. In this review, we summarize that platelet lysates could be valuable candidates for the treatment of a variety of diseases in regenerative medicine.

Electrospun fibers enhanced the paracrine signaling of mesenchymal stem cells for cartilage regeneration

BACKGROUND

Secretome profiles of mesenchymal stem cells (MSCs) are reflective of their local microenvironments. These biologically active factors exert an impact on the surrounding cells, eliciting regenerative responses that create an opportunity for exploiting MSCs towards a cell-free therapy for cartilage regeneration. The conventional method of culturing MSCs on a tissue culture plate (TCP) does not provide the physiological microenvironment for optimum secretome production. In this study, we explored the potential of electrospun fiber sheets with specific orientation in influencing the MSC secretome production and its therapeutic value in repairing cartilage.

METHODS

Conditioned media (CM) were generated from MSCs cultured either on TCP or electrospun fiber sheets of distinct aligned or random fiber orientation. The paracrine potential of CM in affecting chondrogenic differentiation, migration, proliferation, inflammatory modulation, and survival of MSCs and chondrocytes was assessed. The involvement of FAK and ERK mechanotransduction pathways in modulating MSC secretome were also investigated.

RESULTS

We showed that conditioned media of MSCs cultured on electrospun fiber sheets compared to that generated from TCP have improved secretome yield and profile, which enhanced the migration and proliferation of MSCs and chondrocytes, promoted MSC chondrogenesis, mitigated inflammation in both MSCs and chondrocytes, as well as protected chondrocytes from apoptosis. Amongst the fiber sheet-generated CM, aligned fiber-generated CM (ACM) was better at promoting cell proliferation and augmenting MSC chondrogenesis, while randomly oriented fiber-generated CM (RCM) was more efficient in mitigating the inflammation assault. FAK and ERK signalings were shown to participate in the modulation of MSC morphology and its secretome production.

CONCLUSIONS

This study demonstrates topographical-dependent MSC paracrine activities and the potential of employing electrospun fiber sheets to improve the MSC secretome for cartilage regeneration.

Platelets Facilitate the Wound-Healing Capability of Mesenchymal Stem Cells by Mitochondrial Transfer and Metabolic Reprogramming

Platelets are known to enhance the wound-healing activity of mesenchymal stem cells (MSCs). However, the mechanism by which platelets improve the therapeutic potential of MSCs has not been elucidated. Here, we provide evidence that, upon their activation, platelets transfer respiratory-competent mitochondria to MSCs primarily via dynamin-dependent clathrin-mediated endocytosis. We found that this process enhances the therapeutic efficacy of MSCs following their engraftment in several mouse models of tissue injury, including full-thickness cutaneous wound and dystrophic skeletal muscle. By combining in vitro and in vivo experiments, we demonstrate that platelet-derived mitochondria promote the pro-angiogenic activity of MSCs via their metabolic remodeling. Notably, we show that activation of the de novo fatty acid synthesis pathway is required for increased secretion of pro-angiogenic factors by platelet-preconditioned MSCs. These results reveal a new mechanism by which platelets potentiate MSC properties and underline the importance of testing platelet mitochondria quality prior to their clinical use.

Platelet-derived biomaterials-mediated improvement of bone injury through migratory ability of embryonic fibroblasts: in vitro and in vivo evidence

Bony injuries lead to compromised skeletal functional ability which further increase in aging population due to decreased bone mineral density. Therefore, we aimed to investigate the therapeutic potential of platelet-derived biomaterials (PDB) against bone injury. Specifically, we assessed the impact of PDB on osteo-inductive characteristics and migration of mouse embryonic fibroblasts (MEFs). Osteogenic lineage, matrix mineralization and cell migration were determined by gene markers (RUNX2, OPN and OCN), alizarin Red S staining, and migration markers (FAK, pFAK and Src) and EMT markers, respectively. The therapeutic impact of TGF-β1, a key component of PDB, was confirmed by employing inhibitor of TGF-β receptor I (Ti). Molecular imaging-based in vivo cellular migration in mice was determined by establishing bone injury at right femurs. Results showed that PDB markedly increased expression of osteogenic markers, matrix mineralization, migration and EMT markers, revealing higher osteogenic and migratory potential of PDB-treated MEFs. In vivo cell migration was manifested by expression of migratory factors, SDF-1 and CXCR4. Compared to control, PDB-treated mice exhibited higher bone density and volume. Ti treatment inhibited both migration and osteogenic potential of MEFs, affirming impact of TGF-β1. Collectively, our study clearly indicated PDB-rescued bone injury through enhancing migratory potential of MEFs and osteogenesis.

Paracrine Interactions Involved in Human Induced Pluripotent Stem Cells Differentiation into Chondrocytes

Osteoarthritis (OA), as a degenerative joint disease, is the most common form of joint disorder that causes pain, stiffness, and other symptoms associated with OA. Various genetic, biomechanical, and environmental factors have a relevant role in the development of OA. To date, extensive efforts are currently being made to overcome the poor self-healing capacity of articular cartilage. Despite the pivotal role of chondrocytes, their proliferation and repair capacity after tissue injury are limited. Therefore, the development of new strategies to overcome these constraints is urgently needed. Recent advances in regenerative medicine suggest that pluripotent stem cells are promising stem cell sources for cartilage repair. Pluripotent stem cells are undifferentiated cells that have the capacity to differentiate into different types of cells and can self-renew indefinitely. In the past few decades, numerous attempts have been made to regenerate articular cartilage by using induced pluripotent stem cells (iPSCs). The potential applications of patient-specific iPSCs hold great promise for regenerative medicine and OA treatment. However, there are different culture conditions for the preparation and characterization of human iPSCs-derived chondrocytes (hiChondrocytes). Recent biochemical analyses reported that several paracrine factors such as TGFb, BMPs, WNT, Ihh, and Runx have been shown to be involved in cartilage cell proliferation and differentiation from human iPSCs. In this review, we summarize and discuss the paracrine interactions involved in human iPSCs differentiation into chondrocytes in different cell culture media.

Effects mediated by the α7 nicotinic acetylcholine receptor on cell proliferation and migration in rat adipose-derived stem cells

Adipose-derived stem cells (ASCs) are an attractive source for regenerative medicine as they can be easily isolated, rapidly expandable in culture and show excellent in vitro differentiation potential. Acetylcholine (ACh), one of the main neurotransmitters in central and peripheral nervous systems, plays key roles in the control of several physiological processes also in non-neural tissues. As demonstrated in our previous studies, ACh can contribute to the rat ASCs physiology, negatively modulating ASCs proliferation and migration via M2 muscarinic receptor (mAChR) activation. In the present work we show that rat ASCs also express α7 nicotinic receptors (nAChRs). In particular, we have investigated the effects mediated by the selective activation of α7 nAChRs, which causes a reduction of ASC proliferation without affecting cell survival and morphology, and significantly promotes cell migration via upregulation of the CXCR4 expression. Interestingly, the activation of the α7 nAChR also upregulates the expression of M2 mAChR protein, indicating a cooperation between muscarinic and nicotinic receptors in the inhibition of ASC proliferation.

Overexpression of PLIN1 Promotes Lipid Metabolism in Bovine Adipocytes

Perilipin 1 (PLIN1) is a protein encoded by the PLIN1 gene in eukaryotes. PLIN1 is a member of the PAT protein family, a family of proteins related to lipid droplet (LD) surface proteins. PLIN1 phosphorylation plays a vital role during fat metabolism of adipose tissue lipolysis and fat storage in adipocytes. However, to further explore the regulation of the PLIN1 gene on the proliferation, differentiation and lipid metabolism of bovine adipocytes. In this study, the mRNA expression of PLIN1, at day six, was the highest during bovine adipocyte differentiation. Moreover, PLIN1 can promote the proliferation and differentiation of preadipocytes in cattle. On the sixth day, after transfection with, and overexpression of, the PLIN1 gene in bovine preadipocytes via adenovirus, cell samples were collected, and transcriptome sequencing was performed. A total of 1923 differentially expressed genes were detected. Through GO and KEGG pathway analysis, the differentially expressed genes were established to be mainly enriched in the AMPK, Wnt, and PPAR signaling pathways related to fat proliferation and differentiation. In conclusion, at the transcriptional level, PLIN1 plays an important role in regulating fat proliferation and metabolism. Additionally, the sequencing results screened new differentially expressed genes related to fat metabolism, providing theoretical support for molecular breeding of Qinchuan beef cattle.

Actomyosin and the MRTF-SRF pathway downregulate FGFR1 in mesenchymal stromal cells

Both biological and mechanical signals are known to influence cell proliferation. However, biological signals are mostly studied in two-dimensions (2D) and the interplay between these different pathways is largely unstudied. Here, we investigated the influence of the cell culture environment on the response to bFGF, a widely studied and important proliferation growth factor. We observed that human mesenchymal stromal cells (hMSCs), but not fibroblasts, lose the ability to respond to soluble or covalently bound bFGF when cultured on microfibrillar substrates. This behavior correlated with a downregulation of FGF receptor 1 (FGFR1) expression of hMSCs on microfibrillar substrates. Inhibition of actomyosin or the MRTF/SRF pathway decreased FGFR1 expression in hMSCs, fibroblasts and MG63 cells. To our knowledge, this is the first time FGFR1 expression is shown to be regulated through a mechanosensitive pathway in hMSCs. These results add to the sparse literature on FGFR1 regulation and potentially aid designing tissue engineering constructs that better control cell proliferation.