Effect of Activated Immunocompetent Cells on the Content of Multipotent Stromal Cells in Splenic Transplants of CBA and CBA/N Mice Administered with Polyvinylpyrrolidone

One day after intraperitoneal injection of polyvinylpyrrolidone (PVP) to recipient CBA and CBA/N mice, the count of multipotent stromal cells (MSC) in the 4-month-old splenic transplants was minimum in CBA/N→CBA/N group in comparison with the transplants of intact recipients (0.6 from the control level), but increased by 2.3, 3.2, and 3.7 times in CBA/N→CBA, CBA→CBA, and CBA→CBA/N groups, respectively. In the blood serum of recipient CBA/N mice with 4-month splenic transplants of CBA donors, the levels of some cytokines (IL-5, TNFα, and IL-2) was significantly increased 1 and 24 h after PVP injection in contrast to mice with bone marrow transplants, which attests to activation of the innate immunity mechanisms in this (splenic) transplantation variant. Probably, this phenomenon can be explained by the fact that the splenic transplants contain a sufficient number of CD⁺B-1a lymphocytes that can restore the response of recipient CBA/N mice to PVP. Thus, similar to bone marrow transplants [5], MSC count in splenic transplants increased only in groups, where the recipients were capable of responding to PVP. In other words, after injection of PVP to recipient mice, MSC counts in the spleen and bone marrow at this moment are determined by availability of activated immunocompetent cells. Overall, the novel data attest to close relationships between the stromal tissue of hematopoietic and lymphoid organs, on the one hand, and immune system, on the other.

Possible Kidney Complications after Application of Cell Technologies for the Repair of the Resected Liver

The state of rat kidneys after injection of bone marrow multipotent stromal cells (MSC) labeled with Vybrant CM-Dil into intact or resected liver was studied by fluorescence microscopy. The main structural changes in the kidneys after MSC injection into intact and partially resected liver manifested as granular dystrophy and necrobiotic/necrotic changes in single epithelial cells of the distal tubules and collecting ducts, thrombosis of some vessels, progression of an ascending urinary tract infection (detection of dust-like fluorescent objects), which can be due to the immunomodulating or even immunosuppressive influence of MSC and their detritus. MSC injected into the intact or resected liver, as well as the products of their degradation were not detected in the kidneys at all terms of observation. After injection of MSC into partially resected liver, manifestations of bacterial contamination of the renal medulla appeared later. The injection of MSC into the liver can be complicated by thrombosis of the renal vessels, which should be taken into account when using this administration route in the cell therapy.

Dissemination of Multipotent Stromal Cells in the Organism after Their Injection into Intact and Resected Liver in the Experiment

The possibility of dissemination of bone marrow multipotent stromal cells stained with Vybrant CM-Dil after injection into an intact and resected liver was studied using luminescence microscopy. Labeled cells were found in the kidneys, spleen, lungs, axillary, mesenteric, and inguinal lymph nodes. We observed dissemination of multipotent stromal cells and their detritus throughout the body that occurred only after filtration in the lungs, where most cells underwent destruction. Perivascularly located macrophages in various organs can phagocytize multipotent stromal cells and their detritus from blood vessels. The content of objects labeled with Vybrant CM-Dil in distant organs was significantly lower after multipotent stromal cell injection into the resected liver, which was associated with the deposition of cells in the damaged area of the organ and their partial entry into the abdominal cavity.

Behind the Scenes of Extracellular Vesicle Therapy for Skin Injuries and Disorders

Significance: Skin wounds and disorders compromise the protective functions of skin and patient quality of life. Although accessible on the surface, they are challenging to address due to paucity of effective therapies. Exogenous extracellular vesicles (EVs) and cell-free derivatives of adult multipotent stromal cells (MSCs) are developing as a treatment modality. Knowledge of origin MSCs, EV processing, and mode of action is necessary for directed use of EVs in preclinical studies and methodical translation. Recent Advances: Nanoscale to microscale EVs, although from nonskin cells, induce functional responses in cutaneous wound cellular milieu. EVs allow a shift from cell-based to cell-free/derived modalities by carrying the MSC beneficial factors but eliminating risks associated with MSC transplantation. EVs have demonstrated striking efficacy in resolution of preclinical wound models, specifically within the complexity of skin structure and wound pathology. Critical Issues: To facilitate comparison across studies, tissue sources and processing of MSCs, culture conditions, isolation and preparations of EVs, and vesicle sizes require standardization as these criteria influence EV types and contents, and potentially determine the induced biological responses. Procedural parameters for all steps preceding the actual therapeutic administration may be the key to generating EVs that demonstrate consistent efficacy through known mechanisms. We provide a comprehensive review of such parameters and the subsequent tissue, cellular and molecular impact of the derived EVs in different skin wounds/disorders. Future Directions: We will gain more complete knowledge of EV-induced effects in skin, and specificity for different wounds/conditions. The safety and efficacy of current preclinical xenogenic applications will favor translation into allogenic clinical applications of EVs as a biologic.

New Frontiers in Peripheral Nerve Regeneration: Concerns and Remedies

Topical advances in studying molecular and cellular mechanisms responsible for regeneration in the peripheral nervous system have highlighted the ability of the nervous system to repair itself. Still, serious injuries represent a challenge for the morphological and functional regeneration of peripheral nerves, calling for new treatment strategies that maximize nerve regeneration and recovery. This review presents the canonical view of the basic mechanisms of nerve regeneration and novel data on the role of exosomes and their transferred microRNAs in intracellular communication, regulation of axonal growth, Schwann cell migration and proliferation, and stromal cell functioning. An integrated comprehensive understanding of the current mechanistic underpinnings will open the venue for developing new clinical strategies to ensure full regeneration in the peripheral nervous system.

[The cell technologies in modification of mesh materials used in urology]

Based on the literary analysis, the influence of cellular technologies on the results of implantation of mesh materials was studied. The scientific literature of recent years contains a large amount of data devoted to the study of mesh structures and the possibilities of their modification using multipotent stromal cells (MSC) for implantation into patients for correcting tissue defects and pelvic organ prolapse. However, the ideal implant has not yet been created. Additional studies with a longer follow-up period are needed to determine the most successful and safe methods and materials for the restoration of pathologically altered or lost tissues and the transition to clinical trials. It is also yet to come to an unambiguous understanding of the best sources of MSC, ways for stimulation of proliferation, preservation and delivery of these cells into the necessary tissues of the body, to thoroughly study the causes of inefficiency and the risks of developing various complications, especially in the long term. The progress of urological implantology in modern conditions, of course, will be associated with the introduction of modern materials and technologies, including the using MSC.

Coaxial Alginate Hydrogels: From Self-Assembled 3D Cellular Constructs to Long-Term Storage

Alginate as a versatile naturally occurring biomaterial has found widespread use in the biomedical field due to its unique features such as biocompatibility and biodegradability. The ability of its semipermeable hydrogels to provide a favourable microenvironment for clinically relevant cells made alginate encapsulation a leading technology for immunoisolation, 3D culture, cryopreservation as well as cell and drug delivery. The aim of this work is the evaluation of structural properties and swelling behaviour of the core-shell capsules for the encapsulation of multipotent stromal cells (MSCs), their 3D culture and cryopreservation using slow freezing. The cells were encapsulated in core-shell capsules using coaxial electrospraying, cultured for 35 days and cryopreserved. Cell viability, metabolic activity and cell-cell interactions were analysed. Cryopreservation of MSCs-laden core-shell capsules was performed according to parameters pre-selected on cell-free capsules. The results suggest that core-shell capsules produced from the low viscosity high-G alginate are superior to high-M ones in terms of stability during in vitro culture, as well as to solid beads in terms of promoting formation of viable self-assembled cellular structures and maintenance of MSCs functionality on a long-term basis. The application of 0.3 M sucrose demonstrated a beneficial effect on the integrity of capsules and viability of formed 3D cell assemblies, as compared to 10% dimethyl sulfoxide (DMSO) alone. The proposed workflow from the preparation of core-shell capsules with self-assembled cellular structures to the cryopreservation appears to be a promising strategy for their off-the-shelf availability.

Qualifying Osteogenic Potency Assay Metrics for Human Multipotent Stromal Cells: TGF-β2 a Telling Eligible Biomarker

Potency assays are critical for regenerative medicine, addressing the known challenge of functional heterogeneity among human multipotent stromal cells (hMSC). Necessary laboratory cell expansion allows analysis before implantation in the patient. Levels of induction of five signature gene biomarkers, ALPL, COL1A2, DCN, ELN and RUNX2, constituted a previously reported proof-of-principle osteogenic potency assay. We tested assay modification to enhance reproducibility using six consistent bone marrow derived hBM-MSC and explored applicability to three adipose tissue derived hAT-MSC. Using a potent proprietary osteogenic induction factor, the GUSB/YWAHZ reference gene pair provided real time PCR consistency. The novel assay conditions supported the concept that genes encoding extracellular matrix proteins one week after osteogenic induction were informative. Nonetheless, relatively low induction of COL1A2 and ELN encouraged search for additional biomarkers. TGFB2 mRNA induction, important for osteogenic commitment, was readily quantifiable in both hBM-MSC and hAT-MSC. Combined with DCN, TGFB2 mRNA induction data provided discriminatory power for resolving donor-specific heterogeneity. Histomorphometric decorin and TGF-β2 protein expression patterns in eight-week heterotopic bone implants also discriminated the two non-bone-forming hMSC. We highlight progress towards prompt osteogenic potency assays, needed by current clinical trials to accelerate improved intervention with enhanced stem cell therapy for serious bone fractures.

Gene Expression Signatures of Synovial Fluid Multipotent Stromal Cells in Advanced Knee Osteoarthritis and Following Knee Joint Distraction

Osteoarthritis (OA) is the most common musculoskeletal disorder. Although joint replacement remains the standard of care for knee OA patients, knee joint distraction (KJD), which works by temporarily off-loading the joint for 6–8 weeks, is becoming a novel joint-sparing alternative for younger OA sufferers. The biological mechanisms behind KJD structural improvements remain poorly understood but likely involve joint-resident regenerative cells including multipotent stromal cells (MSCs). In this study, we hypothesized that KJD leads to beneficial cartilage-anabolic and anti-catabolic changes in joint-resident MSCs and investigated gene expression profiles of synovial fluid (SF) MSCs following KJD as compared with baseline. To obtain further insights into the effects of local biomechanics on MSCs present in late OA joints, SF MSC gene expression was studied in a separate OA arthroplasty cohort and compared with subchondral bone (SB) MSCs from medial (more loaded) and lateral (less loaded) femoral condyles from the same joints. In OA arthroplasty cohort (n = 12 patients), SF MSCs expressed lower levels of ossification- and hypotrophy-related genes [bone sialoprotein (IBSP), parathyroid hormone 1 receptor (PTH1R), and runt-related transcription factor 2 (RUNX2)] than did SB MSCs. Interestingly, SF MSCs expressed 5- to 50-fold higher levels of transcripts for classical extracellular matrix turnover molecules matrix metalloproteinase 1 (MMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), and tissue inhibitor of metalloproteinase-3 (TIMP3), all (p < 0.05) potentially indicating greater cartilage remodeling ability of OA SF MSCs, compared with SB MSCs. In KJD cohort (n = 9 patients), joint off-loading resulted in sustained, significant increase in SF MSC colonies’ sizes and densities and a notable transcript upregulation of key cartilage core protein aggrecan (ACAN) (weeks 3 and 6), as well as reduction in pro-inflammatory C–C motif chemokine ligand 2 (CCL2) expression (weeks 3 and 6). Additionally, early KJD changes (week 3) were marked by significant increases in MSC chondrogenic commitment markers gremlin 1 (GREM1) and growth differentiation factor 5 (GDF5). In combination, our results reveal distinct transcriptomes on joint-resident MSCs from different biomechanical environments and show that 6-week joint off-loading leads to transcriptional changes in SF MSCs that may be beneficial for cartilage regeneration. Biomechanical factors should be certainly considered in the development of novel MSC-based therapies for OA.

Functional Heterogeneity of Protein Kinase A Activation in Multipotent Stromal Cells

Multipotent stromal cells (MSC) demonstrate remarkable functional heterogeneity; however, its molecular mechanisms remain largely obscure. In this study, we explored MSC response to hormones, which activate Gs-protein / cyclic AMP (cAMP) / protein kinase A (PKA) dependent signaling, at the single cell level using genetically encoded biosensor PKA-Spark. For the first time, we demonstrated that about half of cultured MSCs are not able to activate the cAMP/PKA pathway, possibly due to the limited availability of adenylyl cyclases. Using this approach, we showed that MSC subpopulations responding to various hormones largely overlapped, and the share of responding cells did not exceed 40%. Using clonal analysis, we showed that signaling heterogeneity of MSC could be formed de novo within 2 weeks.

[Liver regeneration after resection in clinical and experimental conditions]

The researches devoted to postoperative liver regeneration and influence in this process were analyzed. Liver injury is followed by hypertrophy of residual liver parenchyma. The use of various cytokines is perspective for activation, acceleration and inhibition of liver recovery. Cellular technologies in the treatment of liver diseases can affect its repair. Moreover, these methods could make unnecessary resection and transplantation of liver in certain cases. It is generally accepted that the main effect of multipotent stromal cells (MSC) in liver failure is associated with their differentiation to the cellular elements of this organ. At the same time, recent reports revealed that MSC injection to the liver is followed by their quick death, dissemination to other organs and tissues or even elimination from the organism. Regeneration of non-parenchymal structures (vascular network and bile ducts) should be considered in addition to functional recovery of liver parenchyma after resection. Clarification of indications and contraindications for MSC therapy, as well as prevention of possible complications associated with cellular technologies are required.

Characterization of a Vimentinhigh /Nestinhigh proteome and tissue regenerative secretome generated by human pancreas-derived mesenchymal stromal cells

Multipotent/mesenchymal stromal cells (MSCs) exist within a variety of postnatal tissues; however, global proteomic analyses comparing tissue-specific MSC are limited. Using human bone marrow (BM)-derived MSCs as a gold standard, we used label-free mass spectrometry and functional assays to characterize the proteome, secretome, and corresponding function of human pancreas-derived MSCs (Panc-MSCs) with a classical phenotype (CD90+/CD73+/CD105+/CD45-/CD31-). Both MSC subtypes expressed mesenchymal markers vimentin, α-SMA, and STRO-1; however, expression of nestin was increased in Panc-MSCs. Accordingly, these Vimentin^high /Nestin^high cells were isolated from fresh human pancreatic islet and non-islet tissues. Next, we identified expression of >60 CD markers shared between Panc-MSCs and BM-MSCs, including validated expression of CD14. An additional 19 CD markers were differentially expressed, including reduced pericyte-marker CD146 expression on Panc-MSCs. Panc-MSCs also showed reduced expression of proteins involved in lipid and retinoid metabolism. Accordingly, Panc-MSCs showed restricted responses to adipogenic stimuli in vitro, although both MSC types demonstrated trilineage differentiation. In contrast, Panc-MSCs demonstrated accelerated growth kinetics and competency to pro-neurogenic stimuli in vitro. The secretome of Panc-MSCs was highly enriched for proteins associated with vascular development, wound healing and chemotaxis. Similar to BM-MSCs, Panc-MSCs conditioned media augmented endothelial cell survival, proliferation, and tubule formation in vitro. Importantly, the secretome of both MSC types was capable of stimulating chemotactic infiltration of murine endothelial cells in vivo and reduced hyperglycemia in STZ-treated mice following intrapancreatic injection. Overall, this study provides foundational knowledge to develop Panc-MSCs as a unique MSC subtype with functional properties beneficial in regenerative medicine for diabetes and vascular disease.

Understanding and leveraging cell metabolism to enhance mesenchymal stem cell transplantation survival in tissue engineering and regenerative medicine applications

In tissue engineering and regenerative medicine, stem cell-specifically, mesenchymal stromal/stem cells (MSCs)-therapies have fallen short of their initial promise and hype. The observed marginal, to no benefit, success in several applications has been attributed primarily to poor cell survival and engraftment at transplantation sites. MSCs have a metabolism that is flexible enough to enable them to fulfill their various cellular functions and remarkably sensitive to different cellular and environmental cues. At the transplantation sites, MSCs experience hostile environments devoid or, at the very least, severely depleted of oxygen and nutrients. The impact of this particular setting on MSC metabolism ultimately affects their survival and function. In order to develop the next generation of cell-delivery materials and methods, scientists must have a better understanding of the metabolic switches MSCs experience upon transplantation. By designing treatment strategies with cell metabolism in mind, scientists may improve survival and the overall therapeutic potential of MSCs. Here, we provide a comprehensive review of plausible metabolic switches in response to implantation and of the various strategies currently used to leverage MSC metabolism to improve stem cell-based therapeutics.

Effect of Non-Thermal Plasma on Proliferative Activity and Adhesion of Multipotent Stromal Cells to Scaffolds Developed for Tissue-Engineered Constructs

We studied the effect of non-thermal argon plasma on proliferative activity of bone marrow multipotent stromal cells in vitro. Treatment of stromal cell suspension with pure argon did not affect their proliferation. The cells treated with non-thermal argon plasma and explanted in the treatment medium demonstrated growth inhibition by 30-40% in comparison with the control. Multipotent stromal cells treated with plasma and after centrifugation explanted in normal medium within 12 min demonstrated accelerated growth. The total cell growth from the pellet and supernatant significantly exceeded the control values. We also analyzed adhesion and proliferative activity of multipotent stromal cells treated with non-thermal plasma on bioresorbable carriers. The cells adhered and proliferated on all types of studied samples. Adhesion properties of scaffolds differed. Caprolactone was found to be the most suitable material for adhesion and proliferation of multipotent stromal cells.

In Vivo Labeling by CD73 Marks Multipotent Stromal Cells and Highlights Endothelial Heterogeneity in the Bone Marrow Niche

Despite much work studying ex vivo multipotent stromal cells (MSCs), the identity and characteristics of MSCs in vivo are not well defined. Here, we generated a CD73-EGFP reporter mouse to address these questions and found EGFP⁺ MSCs in various organs. In vivo, EGFP⁺ mesenchymal cells were observed in fetal and adult bones at proliferative ossification sites, while in solid organs EGFP⁺ cells exhibited a perivascular distribution pattern. EGFP⁺ cells from the bone compartment could be clonally expanded ex vivo from single cells and displayed trilineage differentiation potential. Moreover, in the central bone marrow CD73-EGFP⁺ specifically labeled sinusoidal endothelial cells, thought to be a critical component of the hematopoietic stem cell niche. Purification and molecular characterization of this CD73-EGFP⁺ population revealed an endothelial subtype that also displays a mesenchymal signature, highlighting endothelial cell heterogeneity in the marrow. Thus, the CD73-EGFP mouse is a powerful tool for studying MSCs and sinusoidal endothelium.

Intravenous administration of multipotent stromal cells and bone allograft modification to enhance allograft healing

Aim: This study investigated a coordinated strategy of revitalizing bone allograft with circulating multipotent stromal cells (MSCs). Materials & methods: After chemotactic and releasing assessments, stromal cell-derived factor 1 and platelet-derived growth factor BB in copolymers were coated on the bone allograft (Allo_S-P). Allograft coated with copolymers alone (Allo), as controls, or Allo_S-P was implanted into the femur of athymic mice, which received intravenous injections of human MSCs or saline at weeks 1, 2 and 3. Results: At week 8, the total callus volume (both cartilaginous and bony callus) around the allograft was the largest in the Allo_S-P + MSC group (p < 0.05). Conclusion: Coating bone allograft with stromal cell-derived factor 1 and platelet-derived growth factor BB and intravenous injections of MSCs improved allograft incorporation.

DMSO-Free Cryopreservation of Human Umbilical Cord Tissue

Human umbilical cord represents a source of multipotent stromal cells of a supreme therapeutic potential. The cells can be isolated from either fresh or cryopreserved umbilical cord tissues. DMSO is a cryoprotectant most commonly used for preservation of umbilical cord tissues; however, cyto- and genotoxicity of this compound is evident and well documented. In the present study we performed successful cryopreservation of the umbilical cord tissue using other cryoprotectants: propylene glycol, ethylene glycol, and glycerol. Of these, 1.5 M ethylene glycol and 20% glycerol turned out to be the best in terms of the preservation of living cells within the frozen tissue, early onset of migration of these cells out of the thawed explants, and overall efficacy of multipotent stromal cell isolation. Cryobanking of tissues can improve availability of multiple cell products for medical purposes and promote the development of personalized medicine.

FGF2 Induces Migration of Human Bone Marrow Stromal Cells by Increasing Core Fucosylations on N-Glycans of Integrins

Since hundreds of clinical trials are investigating the use of multipotent stromal cells (MSCs) for therapeutic purposes, effective delivery of the cells to target tissues is critical. We have found an unexplored mechanism, by which basic fibroblast growth factor (FGF2) induces expression of fucosyltransferase 8 (FUT8) to increase core fucosylations of N-linked glycans of membrane-associated proteins, including several integrin subunits. Gain- and loss-of-function experiments show that FUT8 is both necessary and sufficient to induce migration of MSCs. Silencing FUT8 also affects migration of MSCs in zebrafish embryos and a murine bone fracture model. Finally, we use in silico modeling to show that core fucosylations restrict the degrees of freedom of glycans on the integrin's surface, hence stabilizing glycans on a specific position. Altogether, we show a mechanism whereby FGF2 promotes migration of MSCs by modifying N-glycans. This work may help improve delivery of MSCs in therapeutic settings.

In Vitro Modeling of Co-Transplantation of Multipotent Stromal Mesenchymal Cells from Orbital Fat Pad and Lipoaspirate of Human Subcutaneous Adipose Tissue in Organ Culture in Collagen Gel

The interplay of multipotent stromal cells derived from the orbital fat pads and cells of the lipoaspirate from the subcutaneous adipose tissue was studied using in vitro co-transplantation model in an organ culture in a collagen gel. Microscopy findings and intensity of apoptosis and cell proliferation in cultures of lipoaspirate with and without multipotent stromal cells showed that the cells maintained their viability, proliferation capacity, and cytokine secretion activity. Higher proliferatitive activity of cells in cocultures promotes renewal of fat transplant cells and can help to maintain its stable volume in delayed terms after transplantation.

typhimurium Antigen Complex In Vivo and Maintains High Concentration of IL-10 and Th1 Cytokines

Pretreatment with the active substance of antiviral preparation Kagocel, inductor of type I endogenous IFN, in a daily therapeutic dose (30 μg/mouse) 3 h prior to administration of S. typhimurium antigens to CBA mice reduced the number of bone marrow multipotent stromal cell (significantly increased by 3.2 times on the next day after antigen injection) to the initial level. Thus, activation of the stromal tissue induced by administration of the bacterial antigen was blocked. In addition, preliminary administration of Kagocel modulated the cytokine profile of the blood serum affected by S. typhimurium antigens: reduced 1.6-fold elevated concentration a proinflammatory cytokine TNFα to the control level (in 4 h after antigen injection) and maintained this level in 20 h after antigen administration. Kagocel also maintained the concentration of anti-inflammatory cytokine IL-10 at the level surpassing the normal by 1.6 times and high concentrations of Th1 cytokines (IL-2, IFNγ, and IL-12). These results suggest that Kagocel can reduce the immune response to bacterial antigens (similar to type I IFN [7]), which can contribute to its therapeutic and preventive effects in addition to its well documented antiviral activity and then this preparation can be used for the therapy of diseases accompanied by excessive or chronic inflammation.

Reconstruction of Ligament and Tendon Defects Using Cell Technologies

We studied the possibility of restoring the integrity of the Achilles tendon in rabbits using autologous multipotent stromal cells. Collagen or gelatin sponges populated with cells were placed in a resorbable Vicryl mesh tube and this tissue-engineered construct was introduced into a defect of the middle part of the Achilles tendon. In 4 months, histological analysis showed complete regeneration of the tendon with the formation of parallel collagen fibers, spindle-shaped tenocytes, and newly formed vessels.

Villous Chorion: A Potential Source for Pluripotent-like Stromal Cells

Context:

Multipotent stromal cells are isolated from various fetal sources and studied for their phenotypic characterization and ability to differentiate into different lineages.

Aims:

In this study, we aimed to isolate mesenchymal stem or stromal cells (MSCs) from villous chorion, expand under clinical scale level, compared the potency with other source of fetal-derived MSCs and studied their differentiation capabilities to form all three germ layers.

Subjects and Methods:

Placenta obtained from C-section was used to isolate villous chorion-MSCs (VC-MSCs) were expanded up to tenth passage and their characteristics were assessed by proliferation rate and phenotypic characterization using fluorescence-activated cell sorting and also expanded MSCs were analyzed for differentiated into all three germ layers by cytochemical staining.

Results:

Stem cell isolated from VC yielded up to 2.16 × 10⁹ cells at second passage and 3.06–4.23 × 10⁴ cells/cm² at tenth passage. The total yield of cells with all three sources analysis showed that VC has a low yield at second passage compared to amniotic membrane and Wharton's jelly, but the VC-MSCs yield significant amount in lesser days. The phenotypic characterization revealed positive for CD73, CD90, and CD105 and negative for CD79, CD34, CD45, human leukocyte antigen-DR proving their stemness even at tenth passage. They can able to differentiate into ectodermic neural cells, endodermic hepatocytes, and mesodermal differentiation of chondrocytes, adipocytes, and osteogenic cells proving their ability to differentiate into all three germ layers.

Conclusions:

This result suggests that the VC-MSCs are ideal source of stem cells with similar characteristics such as other adult stem cells. Thus, VC-derived MSCs can be potential clinical source in regenerative medicine.

Identification of a distinct subpopulation of fibroblasts from murine dermis: CD73(-) CD105(+) as potential marker of dermal fibroblasts subset with multipotency

Skin dermis includes various types of multipotent stromal cells (MSCs) and a subpopulation of dermal fibroblasts that exhibit the ability to differentiate. However, characterization of this dermal fibroblast subtype remains less understood. In this study, we isolated dermal cells from the skin of newborn C57/B6 mice and investigated their characteristics. Isolated murine dermal cells exhibited a fibroblast phenotype as judged by accepted criteria including a lack of MSC-related antigens and the differentiation potential of MSCs, and the positive expression of fibroblast markers. A comparative analysis demonstrated that CD73(-) CD105(+) but not CD73(-) CD105(-) dermal fibroblasts exhibited some of the functional properties of MSCs. Furthermore, the multipotent phenotype of CD73(-) CD105(+) cells was diminished by treatment of CD105 siRNA and shRNA, indicating that CD105 expression was critical for the retention of differentiation potential of those cells. Overall, these results suggest that CD73(-) CD105(+) cells are a distinct subset of dermal fibroblasts with multipotency and that their surface antigens could help to classify this subpopulation. These cells may contribute to the regeneration of damaged tissue.

Sternal bone marrow derived equine multipotent mesenchymal stromal cells (MSCs): investigations considering the sampling site and the use of different culture media

Aspiration of equine sternal bone marrow is required for the cultivation of bone marrow‐derived multipotent mesenchymal stromal cells (BM‐MSCs) for regenerative therapies. For bone marrow aspiration as well as for MSC cultivation, there is a need to optimize techniques and protocols to enhance MSC harvest at minimized culture times. In a comparative study bone marrow aspirates from sternebra 4 and 5 were collected at two different positions within the sternebrae, either from 10 mm or from 30 mm dorsal from the ventral margin of the sternebrae. Accuracy of the puncture depth was confirmed by ultrasonography and computed tomography. Isolated MSCs were cultivated using media supplemented with three alternative sera, i.e. fetal calf serum, standardized horse serum and autologous serum. Due to morphological characteristics (spherical shape, only thin layer of hyaline cartilage at the ventral site, reliable bone marrow aspiration from only 10 mm intraosseous depth), sternebra 5 appeared most suitable for bone marrow aspiration. Cultivation and expansion of BM‐MSCs was most efficient using fetal calf serum.

Pre-activated human mesenchymal stromal cells in combination with doxorubicin synergistically enhance tumor-suppressive activity in mice

BACKGROUND AIMS

Previously, we showed that human mesenchymal stromal cells (hMSCs) were activated to express tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) upon TNF-α stimulation, induced cell death in triple-negative breast cancer (TNBC) MDA-MB-231 cells (MDA), and RNA released from apoptotic MDA further increased TRAIL expression in hMSCs. This feed-forward stimulation increased apoptosis in MDA cells. Here, we tested whether TRAIL-expressing hMSCs, in combination with a sub-toxic-dose of a chemotherapy drug doxorubicin, would overcome TRAIL resistance and create synergistic effects on targeting metastatic TNBC.

METHODS

To optimize conditions for the combination treatment, we (i) selected an optimal condition to activate hMSCs for TRAIL expression, (ii) selected an optimal dose of doxorubicin treatment, (iii) examined underlying mechanisms in vitro and (iv) tested the efficacy of the optimized conditions in a xenograft mouse model of human breast cancer lung metastasis.

RESULTS

The results showed that DNA fragments from apoptotic MDA triggered hMSCs to increase further TRAIL expression in an absent in melanoma 2 (AIM2)-dependent manner, and thus higher TRAIL-expressing hMSCs stimulated with synthetic DNA, poly(deoxyadenylic-deoxythymidylic) acid [poly(dA:dT)], more effectively suppressed tumor progression in vivo. Furthermore, activated hMSCs increased apoptosis in MDA cells when combined with a sub-toxic dose of doxorubicin, which was mediated by up-regulating TRAIL and Fas-related pathways. When we combined the optimized conditions, pre-activated hMSCs with poly (dA:dT) synergistically reduced tumor burden even with minimal doxorubicin treatment in a xenograft mouse model of human breast cancer lung metastasis.

CONCLUSIONS

These results suggest that the treatment of hMSCs with a sub-toxic dose of doxorubicin can overcome TRAIL resistance and be a potential novel therapy for TNBC metastasis treatment.

Elimination of allogeneic multipotent stromal cells by host macrophages in different models of regeneration

Allogeneic multipotent stromal cells were previously thought to be poorly recognized by host immune system; the prolonged survival in host environments was explained by their immune privileged status. As long as the concept is currently reconsidered, the routes of elimination of allogeneic multipotent stromal cells by host immunity must be taken into account. This is necessary for correct comprehension of their therapeutic action. The study was focused upon survival of umbilical cord-derived allogeneic multipotent stromal cells in different rat models of tissue regeneration induced by partial hepatectomy or by critical limb ischemia. The observations were carried out by means of vital labeling of the cells with PKH26 prior to injection, in combination with differential immunostaining of host macrophages with anti-CD68 antibody. According to the results, allogeneic multipotent stromal cells are specifically eliminated by host immune system; the efficacy can reach 100%. Massive clearance of transplanted cells by host macrophages is accompanied by appropriation of the label by the latter, and this is a pronounced case of misleading presentation of exogenous label by host cells. The study emphasizes the role of macrophages in host response and also the need of additional criteria for correct data interpretation.

Mechanical regulation of mesenchymal stem cell differentiation

Biophysical cues play a key role in directing the lineage commitment of mesenchymal stem cells or multipotent stromal cells (MSCs), but the mechanotransductive mechanisms at play are still not fully understood. This review article first describes the roles of both substrate mechanics (e.g. stiffness and topography) and extrinsic mechanical cues (e.g. fluid flow, compression, hydrostatic pressure, tension) on the differentiation of MSCs. A specific focus is placed on the role of such factors in regulating the osteogenic, chondrogenic, myogenic and adipogenic differentiation of MSCs. Next, the article focuses on the cellular components, specifically integrins, ion channels, focal adhesions and the cytoskeleton, hypothesized to be involved in MSC mechanotransduction. This review aims to illustrate the strides that have been made in elucidating how MSCs sense and respond to their mechanical environment, and also to identify areas where further research is needed.

The marine sponge-derived inorganic polymers, biosilica and polyphosphate, as morphogenetically active matrices/scaffolds for the differentiation of human multipotent stromal cells: potential application in 3D printing and distraction osteogenesis

The two marine inorganic polymers, biosilica (BS), enzymatically synthesized from ortho-silicate, and polyphosphate (polyP), a likewise enzymatically synthesized polymer consisting of 10 to >100 phosphate residues linked by high-energy phosphoanhydride bonds, have previously been shown to display a morphogenetic effect on osteoblasts. In the present study, the effect of these polymers on the differential differentiation of human multipotent stromal cells (hMSC), mesenchymal stem cells, that had been encapsulated into beads of the biocompatible plant polymer alginate, was studied. The differentiation of the hMSCs in the alginate beads was directed either to the osteogenic cell lineage by exposure to an osteogenic medium (mineralization activation cocktail; differentiation into osteoblasts) or to the chondrogenic cell lineage by incubating in chondrocyte differentiation medium (triggering chondrocyte maturation). Both biosilica and polyP, applied as Ca²⁺ salts, were found to induce an increased mineralization in osteogenic cells; these inorganic polymers display also morphogenetic potential. The effects were substantiated by gene expression studies, which revealed that biosilica and polyP strongly and significantly increase the expression of bone morphogenetic protein 2 (BMP-2) and alkaline phosphatase (ALP) in osteogenic cells, which was significantly more pronounced in osteogenic versus chondrogenic cells. A differential effect of the two polymers was seen on the expression of the two collagen types, I and II. While collagen Type I is highly expressed in osteogenic cells, but not in chondrogenic cells after exposure to biosilica or polyP, the upregulation of the steady-state level of collagen Type II transcripts in chondrogenic cells is comparably stronger than in osteogenic cells. It is concluded that the two polymers, biosilica and polyP, are morphogenetically active additives for the otherwise biologically inert alginate polymer. It is proposed that alginate, supplemented with polyP and/or biosilica, is a suitable biomaterial that promotes the growth and differentiation of hMSCs and might be beneficial for application in 3D tissue printing of hMSCs and for the delivery of hMSCs in fractures, surgically created during distraction osteogenesis.

Mesenchymal stem cells from a hypoxic culture improve and engraft Achilles tendon repair

BACKGROUND

Bone marrow-derived mesenchymal stem cells (MSCs) from humans cultured under hypoxic conditions increase bone healing capacity.

HYPOTHESIS

Rat MSCs cultured under hypoxic conditions increase the tendon healing potential after transplantation into injured Achilles tendons.

STUDY DESIGN

Controlled laboratory study.

METHODS

Biomechanical testing, histological analysis, and bromodeoxyuridine (BrdU) labeling/collagen immunohistochemistry were performed to demonstrate that augmentation of an Achilles tendon rupture site with hypoxic MSCs increases healing capacity compared with normoxic MSCs and controls. Fifty Sprague-Dawley rats were used for the experiments, with 2 rats as the source of bone marrow MSCs. The cut Achilles tendons in the rats were equally divided into 3 groups: hypoxic MSC, normoxic MSC, and nontreated (vehicle control). The uncut tendons served as normal uncut controls. Outcome measures included mechanical testing in 24 rats, histological analysis, and BrdU labeling/collagen immunohistochemistry in another 24 rats.

RESULTS

The ultimate failure load in the hypoxic MSC group was significantly greater than that in the nontreated or normoxic MSC group at 2 weeks after incision (2.1 N/mm(2) vs 1.1 N/mm(2) or 1.9 N/mm(2), respectively) and at 4 weeks after incision (5.5 N/mm(2) vs 1.7 N/mm(2) or 2.7 N/mm(2), respectively). The ultimate failure load in the hypoxic MSC group at 4 weeks after incision (5.5 N/mm(2)) was close to but still significantly less than that of the uncut tendon (7.2 N/mm(2)). Histological analysis as determined by the semiquantitative Bonar histopathological grading scale revealed that the hypoxic MSC group underwent a significant improvement in Achilles tendon healing both at 2 and 4 weeks when compared with the nontreated or normoxic MSC group via statistical analysis. Immunohistochemistry further demonstrated that the hypoxic and normoxic MSC groups had stronger immunostaining for type I and type III collagen than did the nontreated group both at 2 and 4 weeks after incision. Moreover, BrdU labeling of MSCs before injection further determined the incorporation and retention of transplanted cells at the rupture site.

CONCLUSION

Transplantation of hypoxic MSCs may be a better and more readily available treatment than normoxic MSCs for Achilles tendon ruptures.

CLINICAL RELEVANCE

The present study provides evidence that transplantation of hypoxic MSCs may be a promising therapy for the treatment of Achilles tendon ruptures.

Endocrine disrupting chemicals and the developmental programming of adipogenesis and obesity

Obesity and related disorders are a burgeoning public health epidemic, particularly in the U.S. Currently 34% of the U.S. population is clinically obese (BMI > 30) and 68% are overweight (BMI > 25), more than double the worldwide average and 10-fold higher than Japan and South Korea. Obesity occurs when energy intake exceeds energy expenditure; however, individuals vary widely in their propensity to gain weight and accrue fat mass, even at identical levels of excess caloric input. Clinical, epidemiological, and biological studies show that obesity is largely programmed during early life, including the intrauterine period. The environmental obesogen hypothesis holds that prenatal or early life exposure to certain endocrine disrupting chemicals can predispose exposed individuals to increased fat mass and obesity. Obesogen exposure can alter the epigenome of multipotent stromal stem cells, biasing them toward the adipocyte lineage at the expense of bone. Hence, humans exposed to obesogens during early life might have an altered stem cell compartment, which is preprogrammed toward an adipogenic fate. This results in a higher steady state number of adipocytes and potentially a lifelong struggle to maintain a healthy weight, which can be exacerbated by societal influences that promote poor diet and inadequate exercise. This review focuses on the developmental origins of the adipocyte, the relationship between adipocyte number and obesity, and how obesogenic chemicals may interfere with the highly efficient homeostatic mechanisms regulating adipocyte number and energy balance.