Viability of equine mesenchymal stem cells during transport and implantation

Dynamic Seeding versus Microinjection of Adipose-Derived Mesenchymal Stem Cells to Acellular Nerve Allograft Reconstructions

BACKGROUND

Functional recovery after acellular nerve allograft (ANA) reconstruction remains inferior to that after autologous nerve grafting, but improved outcomes have been demonstrated with the addition of adipose-derived mesenchymal stem cells (MSCs). Controversy exists regarding the optimal cell-delivery method to enhance ANA reconstructions. The authors investigated the functional recovery of ANAs after dynamic seeding versus microinjection of MSCs.

METHODS

Forty Lewis rats underwent reconstruction of a 10-mm sciatic nerve defect. Animals were divided into 4 groups: reversed autograft, ANA alone, dynamically seeded ANA, or ANA injected with MSCs. During the survival period, ultrasound measurements of the tibialis anterior muscle cross-sectional area were performed. At 12 weeks, functional recovery was evaluated using measurements of ankle contracture, compound muscle action potential, maximum isometric tetanic force, muscle mass, histomorphometry, and immunofluorescence.

RESULTS

The dynamic seeding and microinjection groups demonstrated higher cross-sectional tibialis anterior muscle area recovery than autografts and ANAs alone at week 8 and weeks 4 and 8, respectively. The ankle contracture and compound muscle action potential amplitude recovery were superior in autografts and both seeding methods compared with ANAs alone. The microinjection group demonstrated significantly higher isometric tetanic force, muscle mass, and number of axons compared with ANAs alone. Both seeding methods showed higher CD34 densities compared with ANAs alone. No significant differences between dynamic seeding and microinjection were observed in functional or histologic outcomes.

CONCLUSIONS

The addition of MSCs to ANAs demonstrated earlier motor regeneration compared with autografts and ANAs alone. Both seeding methods improved functional outcomes in the rat sciatic nerve defect model.

Equine bone marrow MSC-derived extracellular vesicles mitigate the inflammatory effects of interleukin-1β on navicular tissues in vitro

BACKGROUND

Safe, efficacious therapy for treating degenerate deep digital flexor tendon (DDFT) and navicular bone fibrocartilage (NBF) in navicular horses is critically necessary. While archetypal orthobiologic therapies for navicular disease are used empirically, their safety and efficacy are unknown. Mesenchymal stem cell-derived extracellular vesicles (EV) may overcome several limitations of current orthobiologic therapies.

OBJECTIVES

To (1) characterise cytokine and growth factor profiles of equine bone marrow mesenchymal stem cell (BM-MSC)-derived extracellular vesicles (BM-EV) and (2) evaluate the in vitro anti-inflammatory and extracellular matrix (ECM) protective potentials of BM-EV on DDFT and NBF explant co-cultures in an IL-1β inflammatory environment.

STUDY DESIGN

In vitro experimental study.

METHODS

Cytokines (IL-1β, IL-6, IL-10, IL-1ra and TNF-α) and growth factors (TGFβ1, VEGF, IGF1 and PDGF) in equine BM-EV isolated via ultracentrifugation and precipitation methods were profiled. Forelimb DDFT and NBF explant co-cultures from seven horses were exposed to media alone, or media containing 2 × 109 ± 0.1 × 109 particles/mL or 10 μg/mL BM-EV (BM-EV), 10 ng/mL interleukin-1β (IL-1β), or IL-1β + BM-EV for 48 h. Co-culture media IL-6, TNF-α, MMP-3, MMP-13 concentrations and explant sulphated glycosaminoglycan (sGAG) content were quantified.

RESULTS

IL-6, IGF1 and VEGF concentrations were 102.1 (37.61-256.2) and 182.3 (163.1-226.3), 72.3 (8-175.6) and 2.4 (0.1-2.6), 108.3 (38.3-709.1) and 211.4 (189.1-318.2) pg/mL per 2 × 109 ± 0.1 × 109 particles/mL or 10 μg/mL 10 μg of BM-EV isolated via ultracentrifugation and precipitation methods, respectively. Co-culture media MMP-3 in BM-EV- (p = 0.03) and BM-EV + IL-1β-treated (p = 0.01) groups were significantly lower than the respective media and IL-1β groups. DDFT explant sGAG content of BM-EV (p = 0.003) and BM-EV + IL-1β groups were significantly higher compared with IL-1β group.

MAIN LIMITATIONS

Specimen numbers are limited, in vitro model may not replicate clinical case conditions, lack of non-MSC-derived EV control group.

CONCLUSIONS

Equine BM-EV contains IL-6 and growth factors, IGF1 and VEGF. The anti-inflammatory and ECM protective potentials of BM-EV were evident as increased IL-6 and decreased MMP-3 concentrations in the DDFT-NBF explant co-culture media. These results support further evaluation of BM-EV as an acellular and 'off-the-shelf' intra-bursal/intrasynovial therapy for navicular pathologies.

The role of intensive care nurses in cellular treatments during the COVID-19 pandemic

BACKGROUND

Today, the use of cellular therapies as an effective treatment in the field of health is increasing. In the COVID-19 pandemic or similar situations, cellular therapies may be sometimes life-saving. The COVID-19 pandemic has shown us that the training of intensive care nurses in special cases, such as cellular therapies, is insufficient.

AIM

The study aimed to determine the duties, responsibilities and training of intensive care nurses on mesenchymal stem cells (MSCs) transplantation to critically ill patients during the COVID-19 pandemic.

STUDY DESIGN

This descriptive and retrospective study was conducted on 107 critically ill patients diagnosed with COVID-19 infection and followed up in the intensive care unit (ICU) between April 2020 and April 2022. Each patient was transplanted MSCs by intravenous infusion three times. Before starting cellular therapy applications, intensive care nurses were selected to work on this treatment modality. Each nurse was given theoretical and practical training by experienced instructors.

RESULTS

Intensive care nurses trained for MSCs transplants took part in the pre-application, preparation, application and post-application period. MSCs were checked by the ICU nurses in the pre-application period. Patients' vital signs, existing catheters, consciousness status and parameters were checked by nurses in the preparation and application period. No side effects and complications were observed in patients during MSCs transplantation and within the first 24 h. Patients' late complications and mortality were recorded by nurses during the post-application periods.

CONCLUSIONS

We recommend that nurses working especially in Level 3 ICUs receive training and certification in cellular therapies, especially in hospitals where advanced/cellular treatments are applied.

RELEVANCE TO CLINICAL PRACTICE

Intensive care nurses are actively involved in every phase of the application of MSCs. Especially before such special practices, which came to the fore with the COVID-19 pandemic, training should be organized for intensive care nurses.

Autologous point-of-care stromal vascular fraction transplantation in dogs with advanced osteoarthritis of the knee and hip joints

OBJECTIVE

The aim of the study was to assess lameness in dogs with advanced osteoarthritis of the hip and knee joints after a single autologous point-of-care transplantation of the Stromal Vascular Fraction (SVF) into the affected joint.

MATERIALS AND METHODS

During a minilaparotomy, 10 g of falciform fat was removed from each patient for each joint to be treated. A modern and time-saving procedure (ARC TM System, InGeneron GmbH, Houston, USA) was used for the in-house preparation of the SVF, so that the isolated cells could be applied to the respective joint within 2 h after fat removal. In total, five knee joints of five patients and seven hip joints of four patients were treated.

RESULTS

Improvement in lameness according to owner questionnaires was seen in 3 of 5 patients with knee joint arthritis and 2 of 4 patients with hip joint arthritis. Based on gait analysis, only one dog with gonarthrosis and one dog with coxarthrosis showed improvement up to a maximum of 3 months after surgery.

CONCLUSION

This is the first case series on the treatment of osteoarthrosis of the knee or hip joint using point-of-care transplantation of the SVF. In individual cases, this method may represent a therapeutic approach for the treatment in dogs with advanced cox- or gonarthrosis, although only a short-term effect can be expected, which calls into question the effort and costs involved.

Mesenchymal stem cells: A promising antimicrobial therapy in veterinary medicine

Growing antimicrobial resistance (AMR) is a threat to human and animal populations citing the limited available options. Alternative antimicrobial options or functional enhancement of currently available antimicrobials remains only options. One of the potential options seems stem cells especially the mesenchymal stem cells (MSCs) that show antimicrobial properties. These cells additionally have pro-healing effects that may plausibly improve healing outcomes. MSCs antimicrobial actions are mediated either through direct cell-cell contact or their secretome that enhances innate immune mediated antimicrobial activities. These cells synergistically enhance efficacy of currently available antimicrobials especially against the biofilms. Reciprocal action from antimicrobials on the MSCs functionality remains poorly understood. Currently, the main limitation with MSCs based therapy is their limited efficacy. This demands further understanding and can be enhanced through biotechnological interventions. One of the interventional options is the 'priming' to enhance MSCs resistance and specific expression potential. The available literature shows potential antimicrobial actions of MSCs both ex vivo as well as in vivo. The studies on veterinary species are very promising although limited by number and extensiveness in details for their utility as standard therapeutic agents. The current review aims to discuss the role of animals in AMR and the potential antimicrobial actions of MSCs in veterinary medicine. The review also discusses the limitations in their utilization as standard therapeutics.

Systematic review and meta-analysis of mesenchymal stromal/stem cells as strategical means for the treatment of COVID-19

BACKGROUND

In coronavirus disease 2019 (COVID-19) patients, elevated levels of inflammatory cytokines from over stimulation of immune cells have become a concern due to the potential outburst of cytokine storm that damages the tissues and organs, especially the lungs. This leads to the manifestation of COVID-19 symptoms, such as pneumonia, acute respiratory distress syndrome (ARDS), multiple organ failure, and eventually death. Mesenchymal stromal/stem cells (MSCs) are currently one of hopeful approaches in treating COVID-19 considering its anti-inflammatory and immunomodulatory functions. On that account, the number of clinical trials concerning the use of MSCs for COVID-19 has been increasing. However, the number of systematic reviews and meta-analysis that specifically discuss its potential as treatment for the disease is still lacking. Therefore, this review will assess the safety and efficacy of MSC administration in COVID-19 patients.

OBJECTIVES

To pool evidence on the safety and efficacy of MSCs in treating COVID-19 by observing MSC-related adverse effects as well as evaluating its effects in reducing inflammatory response and improving pulmonary function.

DATA SOURCES AND METHODS

Following literature search across six databases and one trial register, full-text retrieval, and screening against eligibility criteria, only eight studies were included for data extraction. All eight studies evaluated the use of umbilical cord-derived mesenchymal stromal/stem cell (UC-MSC), infused intravenously. Of these eight studies, six studies were included in meta-analysis on the incidence of mortality, adverse events (AEs), and serious adverse events (SAEs), and the levels of C-reactive protein (CRP) and interleukin (IL)-6. Meta-analysis on pulmonary function was not performed due to insufficient data.

RESULTS

MSC-treated group showed significantly lower risk of mortality than the control group (p = 0.03). No statistical significance was observed on the incidence of AEs (p = 0.78) and SAEs (p = 0.44), and the levels of CRP (p = 0.06) and IL-6 (p = 0.09).

CONCLUSION

MSCs were safe for use, with lower risk of mortality and no association with AEs. Regarding efficacy, descriptive analysis showed indications of improvement on the inflammatory reaction, lung clearance, and oxygenation status despite the lack of statistical significance in meta-analysis of CRP and IL-6. Nevertheless, more studies are needed for affirmation.

REGISTRATION

This systematic review and meta-analysis was registered on the PROSPERO database (no. CRD42022307730).

Shipping Temperature, Time and Media Effects on Equine Wharton’s Jelly and Adipose Tissue Derived Mesenchymal Stromal Cells Characteristics

Simple Summary

Today, the use of horse adipose tissue and Wharton’s jelly-derived mesenchymal stromal cells in veterinary regenerative medicine represents a promising tool. Cells need to be isolated and expanded in vitro in the laboratory to obtain a sufficient amount for clinical application and its characterization. In many cases, laboratories and clinics where the therapy will be performed are in different and far-flung facilities, and the cells must therefore be shipped by a courier. The authors evaluated the effects of different storage conditions, in terms of temperature, time of storage and storage solutions on cell viability, cell growth, differentiation potential and molecular characteristics. The aim was to state the most appropriate storage conditions for transporting adipose tissue and Wharton’s jelly-derived stromal cells, ensuring the maintenance of the stemness features for therapeutic application in horses.

Abstract

To use Mesenchymal Stromal Cells (MSCs) in equine patients, isolation and expansion are performed in a laboratory. Cells are then sent back to the veterinary clinic. The main goal of storage conditions during cell transport is to preserve their biological properties and viability. The aim of this study was to evaluate the effects of storage solutions, temperature and time on the characteristics of equine adipose tissue and Wharton’s jelly-derived MSCs. We compared two different storage solutions (plasma and 0.9% NaCl), two different temperatures (4 °C and room temperature) and three time frames (6, 24, 48 h). Cell viability, colony-forming units, trilineage differentiation, the expression of CD45 and CD90 antigens and adhesion potentials were evaluated. Despite the molecular characterization and differentiation potential were not influenced by storage conditions, viability, colony-forming units and adhesion potential are influenced in different way, depending on MSCs sources. Overall, this study found that, despite equine adipose tissue MSCs being usable after 24 h of storage, cells derived from Wharton’s jelly need to be used within 6 h. Moreover, while for adipose cells the best conservation solutions seems to be plasma, the cell viability of Wharton’s jelly MSCs declined in both saline and plasma solution, confirming their reduced resistance to conservation.

Manufacturing Mesenchymal Stromal Cells for the Treatment of Osteoarthritis in Canine Patients: Challenges and Recommendations

The recent interest in advanced biologic therapies in veterinary medicine has opened up opportunities for new treatment modalities with considerable clinical potential. Studies with mesenchymal stromal cells (MSCs) from animal species have focused on in vitro characterization (mostly following protocols developed for human application), experimental testing in controlled studies and clinical use in veterinary patients. The ability of MSCs to interact with the inflammatory environment through immunomodulatory and paracrine mechanisms makes them a good candidate for treatment of inflammatory musculoskeletal conditions in canine species. Analysis of existing data shows promising results in the treatment of canine hip dysplasia, osteoarthritis and rupture of the cranial cruciate ligament in both sport and companion animals. Despite the absence of clear regulatory frameworks for veterinary advanced therapy medicinal products, there has been an increase in the number of commercial cell-based products that are available for clinical applications, and currently the commercial use of veterinary MSC products has outpaced basic research on characterization of the cell product. In the absence of quality standards for MSCs for use in canine patients, their safety, clinical efficacy and production standards are uncertain, leading to a risk of poor product consistency. To deliver high-quality MSC products for veterinary use in the future, there are critical issues that need to be addressed. By translating standards and strategies applied in human MSC manufacturing to products for veterinary use, in a collaborative effort between stem cell scientists and veterinary researchers and surgeons, we hope to facilitate the development of quality standards. We point out critical issues that need to be addressed, including a much higher level of attention to cell characterization, manufacturing standards and release criteria. We provide a set of recommendations that will contribute to the standardization of cell manufacturing methods and better quality assurance.

Exploring Honeybee Abdominal Anatomy through Micro-CT and Novel Multi-Staining Approaches

Simple Summary

Apis mellifera or western honeybees are insects belonging to the Order Hymenoptera and the most important pollinators worldwide with great implications in natural biodiversity and agriculture due to their importance in pollination and honey production. The characterization of honeybee anatomy with precise tools will allow a better comprehension of the physiology of these insects under different biological conditions. Here, we employed Micro-computed tomography and novel staining methods to define the morphoanatomical characteristics of the worker honeybee abdomen. We defined the 3D and 2Ds structures of the midgut and hindgut and discovered a new cell type called ventricular telocyte, with possible roles in honeybee epithelium maintenance. Overall, we propose that this method will be useful for further investigation of the structure of the honeybee abdomen under a wide variety of environmental conditions.

Abstract

Continuous improvements in morphological and histochemical analyses of Apis mellifera could improve our understanding of the anatomy and physiology of these insects at both the cellular and tissue level. In this work, two different approaches have been performed to add new data on the abdomen of worker bees: (i) Micro-computed tomography (Micro-CT), which allows the identification of small-scale structures (micrometers) with adequate/optimal resolution and avoids sample damage and, (ii) histochemical multi-staining with Periodic Acid-Schiff-Alcian blue, Lactophenol-Saphranin O and pentachrome staining to precisely characterize the histological structures of the midgut and hindgut. Micro-CT allowed high-resolution imaging of anatomical structures of the honeybee abdomen with particular emphasis on the proventriculus and pyloric valves, as well as the connection of the sting apparatus with the terminal abdominal ganglia. Furthermore, the histochemical analyses have allowed for the first-time description of ventricular telocytes in honeybees, a cell type located underneath the midgut epithelium characterized by thin and long cytoplasmic projections called telopodes. Overall, the analysis of these images could help the detailed anatomical description of the cryptic structures of honeybees and also the characterization of changes due to abiotic or biotic stress conditions.

Dynamic seeding versus microinjection of mesenchymal stem cells for acellular nerve allograft: an in vitro comparison

BACKGROUND

Mesenchymal stem cell (MSC)-supplemented acellular nerve allografts (ANA) are a potential strategy to improve the treatment of segmental nerve defects. Prior to clinical translation, optimal cell delivery methods must be defined. While two techniques, dynamic seeding and microinjection, have been described, the seeding efficiency, cell viability, and distribution of MSCs in ANAs are yet to be compared.

METHODS

Sciatic nerve segments of Sprague-Dawley rats were decellularized, and MSCs were harvested from the adipose tissue of Lewis rats. Cell viability was evaluated after injection of MSCs through a 27-gauge needle at different flow rates (10, 5, and 1 µL/min). MSCs were dynamically seeded or longitudinally injected into ANAs. Cell viability, seeding efficiency, and distribution were evaluated using LIVE/DEAD and MTS assays, scanning electron microscopy, and Hoechst staining.

RESULTS

No statistically significant difference in cell viability after injection at different flow rates was seen. After cell delivery, 84.1 ± 3.7% and 87.8 ± 2.8% of MSCs remained viable in the dynamic seeding and microinjection group, respectively (p = 0.41). The seeding efficiency of microinjection (100.4%±5.6) was significantly higher than dynamic seeding (48.1%±8.6) on day 1 (p = 0.001). Dynamic seeding demonstrated a significantly more uniform cell distribution over the course of the ANA compared to microinjection (p = 0.02).

CONCLUSION

MSCs remain viable after both dynamic seeding and microinjection in ANAs. Higher seeding efficiency was observed with microinjection, but dynamic seeding resulted in a more uniform distribution. In vivo studies are required to assess the effect on gene expression profiles and functional motor outcomes.

Effects of carrier solutions on the viability and efficacy of canine adipose-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) have favorable characteristics that render them a potent therapeutic tool. We tested the characteristics of MSCs after temporal storage in various carrier solutions, such as 0.9% saline (saline), 5% dextrose solution (DS), heparin in saline, and Hartmann’s solution, all of which are approved by the U.S. Food and Drug Administration (FDA). Phosphate-buffered saline, which does not have FDA approval, was also used as a carrier solution. We aimed to examine the effects of these solutions on the viability and characteristics of MSCs to evaluate their suitability and efficacy for the storage of canine adipose-derived MSCs (cADMSCs).

Results

We stored the cADMSCs in the test carrier solutions in a time-dependent manner (1, 6, and 12 h) at 4 °C, and analyzed cell confluency, viability, proliferation, self-renewability, and chondrogenic differentiation. Cell confluency was significantly higher in 5% DS and lower in phosphate-buffered saline at 12 h compared to other solutions. cADMSCs stored in saline for 12 h showed the highest viability rate. However, at 12 h, the proliferation rate of cADMSCs was significantly higher after storage in 5% DS and significantly lower after storage in saline, compared to the other solutions. cADMSCs stored in heparin in saline showed superior chondrogenic capacities at 12 h compared to other carrier solutions. The expression levels of the stemness markers, Nanog and Sox2, as well as those of the MSC surface markers, CD90 and CD105, were also affected over time.

Conclusion

Our results suggest that MSCs should be stored in saline, 5% DS, heparin in saline, or Hartmann’s solution at 4 °C, all of which have FDA approval (preferable storage conditions: less than 6 h and no longer than 12 h), rather than storing them in phosphate-buffered saline to ensure high viability and efficacy.

Development of Injectable Polydactyly-Derived Chondrocyte Sheets

We are conducting a clinical study of the use of allogeneic polydactyly-derived chondrocyte sheets (PD sheets) for the repair of articular cartilage damage caused by osteoarthritis. However, the transplantation of PD sheets requires highly invasive surgery. To establish a less invasive treatment, we are currently developing injectable fragments of PD sheets (PD sheets-mini). Polydactyly-derived chondrocytes were seeded in RepCell™ or conventional temperature-responsive inserts and cultured. Cell counts and viability, histology, enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qPCR), and flow cytometry were used to characterize PD sheets-mini and PD sheets collected from each culture. To examine the effects of injection on cell viability, PD sheets-mini were tested in four experimental conditions: non-injection control, 18 gauge (G) needle, 23G needle, and syringe only. PD sheets-mini produced similar amounts of humoral factors as PD sheets. No histological differences were observed between PD sheets and PD sheets-mini. Except for COL2A1, expression of cartilage-related genes did not differ between the two types of PD sheet. No significant differences were observed between injection conditions. PD sheets-mini have characteristics that resemble PD sheets. The cell viability of PD sheets-mini was not significantly affected by needle gauge size. Intra-articular injection may be a feasible, less invasive method to transplant PD sheets-mini.

Mesoscopic heterogeneity in a nanocellulose-containing cell storage medium

A nanocellulose (NC)-containing medium is a promising candidate for cell storage that allows cell floating without any stirring. We here found that the NC medium was spatially heterogeneous in terms of its rheological properties. The characteristic length of the heterogeneity was a few tens of micrometers and it decreased upon sonication treatment. The length scale of the heterogeneity affected the cell suspension; the NC medium having a smaller length scale suppressed the cell sedimentation effectively.

Introducing human adipose-derived mesenchymal stem cells to AvanceⓇ nerve grafts and NeuraGenⓇ nerve guides

BACKGROUND

When direct nerve coaptation is impossible after peripheral nerve injury, autografts, processed allografts, or conduits are used to bridge the nerve gap. The purpose of this study was to examine if human adipose-derived Mesenchymal Stromal/Stem Cells (MSCs) could be introduced to commercially available nerve graft substitutes and to determine cell distribution and the seeding efficiency of a dynamic seeding strategy.

METHODS

MTS assays examined the viability of human MSCs after introduction to the Avance^Ⓡ Nerve Graft and the NeuraGen^Ⓡ Nerve Guide. MSCs were dynamically seeded on nerve substitutes for either 6, 12, or 24 h. Cell counts, live/dead stains, Hoechst stains, and Scanning Electron Microscopy (SEM) revealed the seeding efficiency and the distribution of MSCs after seeding.

RESULTS

The viability of MSCs was not affected by nerve substitutes. Dynamic seeding led to uniformly distributed MSCs over the surface of both nerve substitutes and revealed MSCs on the inner surface of the NeuraGen^Ⓡ Nerve Guides. The maximal seeding efficiency of NeuraGen^Ⓡ Nerve Guides (94%), obtained after 12 h was significantly higher than that of Avance^Ⓡ Nerve Grafts (66%) (p = 0.010).

CONCLUSION

Human MSCs can be dynamically seeded on Avance^Ⓡ Nerve Grafts and NeuraGen^Ⓡ Nerve Guides. The optimal seeding duration was 12 h. MSCs were distributed in a uniform fashion on exposed surfaces. This study demonstrates that human MSCs can be effectively and efficiently seeded onto commercially available nerve autograft substitutes in a timely fashion and sets the stage for the clinical application of MSC-seeded nerve graft substitutes clinically.

Blood type and breed-associated differences in cell marker expression on equine bone marrow-derived mesenchymal stem cells including major histocompatibility complex class II antigen expression

BACKGROUND

As the search for an immune privileged allogeneic donor mesenchymal stem cell (MSC) line continues in equine medicine, the characterization of the cells between different sources becomes important. Our research seeks to more clearly define the MSC marker expression of different equine MSC donors.

METHODS

The bone marrow-derived MSCs from two equine breeds and different blood donor-types were compared over successive culture passages to determine the differential expression of important antigens. Eighteen Thoroughbreds and 18 Standardbreds, including 8 blood donor (erythrocyte Aa, Ca, and Qa antigen negative) horses, were evaluated. Bone marrow was taken from each horse for isolation and culture of MSCs. Samples from passages 2, 4, 6, and 8 were labelled and evaluated by flow cytometry. The cell surface expression of CD11a/18, CD44, CD90 and MHC class II antigens were assessed. Trilineage assays for differentiation into adipogenic, chondrogenic and osteogenic lines were performed to verify characterization of the cells as MSCs.

FINDINGS

There were significant differences in mesenchymal stem cell marker expression between breeds and blood antigen-type groups over time. Standardbred horses showed a significantly lower expression of MHC class II than did Thoroughbred horses at passages 2, 4 and 6. CD90 was significantly higher in universal blood donor Standardbreds as compared to non-blood donor Standardbreds over all time points. All MSC samples showed high expression of CD44 and low expression of CD11a/18.

CONCLUSIONS

Universal blood donor- type Standardbred MSCs from passages 2-4 show the most ideal antigen expression pattern of the horses and passages that we characterized for use as a single treatment of donor bone marrow-derived MSCs. Further work is needed to determine the significance of this differential expression along with the effect of the expression of MHC I on equine bone marrow-derived MSCs.

Strategies of tenogenic differentiation of equine stem cells for tendon repair: current status and challenges

Tendon injuries, as one of the most common orthopedic disorders, are the major cause of early retirement or wastage among sport horses which mainly affect the superficial digital flexor tendon (SDFT). Tendon repair is a slow process, and tendon tissue is often replaced by scar tissue. The current treatment options are often followed by an incomplete recovery that increases the susceptibility to re-injury. Recently, cell therapy has been used in veterinary medicine to treat tendon injuries, although the risk of ectopic bone formation after cell injection is possible in some cases. In vitro tenogenic induction may overcome the mentioned risk in clinical application. Moreover, a better understanding of treatment strategies for musculoskeletal injuries in horse may have future applications for human and vice versa. This comprehensive review outlines the current strategies of stem cell therapy in equine tendon injury and in vitro tenogenic induction of equine stem cell.

Adhesion, distribution, and migration of differentiated and undifferentiated mesenchymal stem cells (MSCs) seeded on nerve allografts

BACKGROUND

Although undifferentiated MSCs and MSCs differentiated into Schwann-like cells have been extensively compared in vitro and in vivo, studies on the ability and efficiency of differentiated MSCs for delivery into nerve allografts are lacking. As this is essential for their clinical potential, the purpose of this study was to determine the ability of MSCs differentiated into Schwann-like cells to be dynamically seeded on decellularized nerve allografts and to compare their seeding potential to that of undifferentiated MSCs.

METHODS

Fifty-six sciatic nerve segments from Sprague Dawley rats were decellularized, and MSCs were harvested from Lewis rat adipose tissue. Control and differentiated MSCs were dynamically seeded on the surface of decellularized allografts. Cell viability, seeding efficiencies, cell adhesion, distribution, and migration were evaluated.

RESULTS

The viability of both cell types was not influenced by the processed nerve allograft. Both cell types achieved maximal seeding efficiency after 12 h of dynamic seeding, albeit that differentiated MSCs had a significantly higher mean seeding efficiency than control MSCs. Dynamic seeding resulted in a uniform distribution of cells among the surface of the nerve allograft. No cells were located inside the nerve allograft after seeding.

CONCLUSION

Differentiated MSCs can be dynamically seeded on the surface of a processed nerve allograft, in a similar fashion as undifferentiated MSCs. Schwann-like differentiated MSCs have a significantly higher seeding efficiency after 12 h of dynamic seeding. We conclude that differentiation of MSCs into Schwann-like cells may improve the seeding strategy and the ability of nerve allografts to support axon regeneration.

Targeted stimulation of MSCs in peripheral nerve repair

Mesenchymal stem cells (MSCs) have considerable translational potential in a wide variety of clinical disciplines and are the cellular foundation of individualized treatments of auto-immune, cardiac, neurologic and musculoskeletal diseases and disorders. While the cellular mechanisms by which MSCs exert their biological effects remain to be ascertained, it has been hypothesized that MSCs are supportive of local tissue repair through secretion of essential growth factors. Therapeutic applications of MSCs in peripheral nerve repair have recently been reported. This review focuses on how MSCs can promote nerve regeneration by conversion into Schwann-like cells, and discusses differentiation methods including delivery and dosing of naive or differentiated MSCs, as well as in vitro and in vivo outcomes. While MSC-based therapies for nerve repair are still in early stages of development, current progress in the field provides encouragement that MSCs may have utility in the treatment of patients with peripheral nerve injury.

Equine Mesenchymal Stem Cells: Properties, Sources, Characterization, and Potential Therapeutic Applications

Properties like sustained multiplication and self-renewal, and homing and multilineage differentiation to undertake repair of the damaged tissues make stem cells the lifeline for any living system. Therefore, stem cell therapy is regarded to carry immense therapeutic potential. Though the dearth of understanding about the basic biological properties and pathways involved in therapeutic benefits currently limit the application of stem cells in humans as well as animals, there are innumerable reports that suggest clinical benefits of stem cell therapy in equine. Among various stem cell sources, currently adult mesenchymal stem cells (MSCs) are preferred for therapeutic application in horse owing to their easy availability, capacity to modulate inflammation, and promote healing. Also the cells carry very limited teratogenic risk compared to the pluripotent stem cells. Mesenchymal stem cells were earlier considered mainly for musculoskeletal tissues, but now may also be utilized in other diverse clinical problems in horse, and the results may be extrapolated even for human medicine. The current review highlights biological properties, sources, mechanisms, and potential therapeutic applications of stem cells in equine practice.

Practical considerations for clinical use of mesenchymal stem cells: From the laboratory to the horse

Since the clinical use of mesenchymal stem cells (MSCs) for treating musculoskeletal injuries is gaining popularity, practitioners should be aware of the factors that may affect MSCs from tissue harvesting for MSC isolation to cell delivery into the injury site. This review provides equine practitioners with up-to-date, practical knowledge for the treatment of equine patients using MSCs. A brief overview of laboratory procedures affecting MSCs is provided, but the main focus is on shipping conditions, routes of administration, injection methods, and which commonly used products can be combined with MSCs and which products should be avoided as they have deleterious effects on cells. There are still several knowledge gaps regarding MSC-based therapies in horses. Therefore, it is important to properly manage the factors which are currently known to affect MSCs, to further strengthen the evidence basis of this treatment.

Cell-Based Therapies for Joint Disease in Veterinary Medicine: What We Have Learned and What We Need to Know

Biological cell-based therapies for the treatment of joint disease in veterinary patients include autologous-conditioned serum, platelet-rich plasma, and expanded or non-expanded mesenchymal stem cell products. This narrative review outlines the processing and known mechanism of action of these therapies and reviews current preclinical and clinical efficacy in joint disease in the context of the processing type and study design. The significance of variation for biological activity and consequently regulatory approval is also discussed. There is significant variation in study outcomes for canine and equine cell-based products derived from whole blood or stem cell sources such as adipose and bone marrow. Variation can be attributed to altering bio-composition due to factors including preparation technique and source. In addition, study design factors like selection of cases with early vs. late stage osteoarthritis (OA), or with intra-articular soft tissue injury, influence outcome variation. In this under-regulated field, variation raises concerns for product safety, consistency, and efficacy. Cell-based therapies used for OA meet the Food and Drug Administration’s (FDA’s) definition of a drug; however, researchers must consider their approach to veterinary cell-based research to meet future regulatory demands. This review explains the USA’s FDA guidelines as an example pathway for cell-based therapies to demonstrate safety, effectiveness, and manufacturing consistency. An understanding of the variation in production consistency, effectiveness, and regulatory concerns is essential for practitioners and researchers to determine what products are indicated for the treatment of joint disease and tactics to improve the quality of future research.

Covalently adaptable elastin-like protein - hyaluronic acid (ELP - HA) hybrid hydrogels with secondary thermoresponsive crosslinking for injectable stem cell delivery

Shear-thinning, self-healing hydrogels are promising vehicles for therapeutic cargo delivery due to their ability to be injected using minimally invasive surgical procedures. We present an injectable hydrogel using a novel combination of dynamic covalent crosslinking with thermoresponsive engineered proteins. Ex situ at room temperature, rapid gelation occurs through dynamic covalent hydrazone bonds by simply mixing two components: hydrazine-modified elastin-like protein (ELP) and aldehyde-modified hyaluronic acid. This hydrogel provides significant mechanical protection to encapsulated human mesenchymal stem cells during syringe needle injection and rapidly recovers after injection to retain the cells homogeneously within a 3D environment. In situ, the ELP undergoes a thermal phase transition, as confirmed by Coherent anti-Stokes Raman scattering microscopy observation of dense ELP thermal aggregates. The formation of the secondary network reinforces the hydrogel and results in a 10-fold slower erosion rate compared to a control hydrogel without secondary thermal crosslinking. This improved structural integrity enables cell culture for three weeks post injection, and encapsulated cells maintain their ability to differentiate into multiple lineages, including chondrogenic, adipogenic, and osteogenic cell types. Together, these data demonstrate the promising potential of ELP-HA hydrogels for injectable stem cell transplantation and tissue regeneration.

Preservation media, durations and cell concentrations of short-term storage affect key features of human adipose-derived mesenchymal stem cells for therapeutic application

Background

Adipose-derived mesenchymal stem cells (ADSCs) have shown great potential in the treatment of various diseases. However, the optimum short-term storage condition of ADSCs in 2∼8 °C is rarely reported. This study aimed at optimizing a short-term storage condition to ensure the viability and function of ADSCs before transplantation.

Methods

Preservation media and durations of storage were evaluated by cell viability, apoptosis, adhesion ability and colony-forming unit (CFU) capacity of ADSCs. The abilities of cell proliferation and differentiation were used to optimize cell concentrations. Optimized preservation condition was evaluated by cell surface markers, cell cycle and immunosuppressive capacity.

Results

A total of 5% human serum albumin in multiple electrolytes (ME + HSA) was the optimized medium with high cell viability, low cluster rate, good adhesion ability and high CFU capacity of ADSCs. Duration of storage should be limited to 24 h to ensure the quality of ADSCs before transplantation. A concentration of 5 × 10⁶ cells/ml was the most suitable cell concentration with low late stage apoptosis, rapid proliferation and good osteogenic and adipogenic differentiation ability. This selected condition did not change surface markers, cell cycle, indoleamine 2, 3-dioxygenase 1 (IDO1) gene expression and kynurenine (Kyn) concentration significantly.

Discussion

In this study, ME + HSA was found to be the best medium, most likely due to the supplement of HSA which could protect cells, the physiological pH (7.4) of ME and sodium gluconate ingredient in ME which could provide energy for cells. Duration should be limited to 24 h because of reduced nutrient supply and increased waste and lactic acid accumulation during prolonged storage. To keep cell proliferation and limit lactic acid accumulation, the proper cell concentration is 5× 10⁶ cells/ml. Surface markers, cell cycle and immunosuppressive capacity did not change significantly after storage using the optimized condition, which confirmed our results that this optimized short-term storage condition of MSCs has a great potential for the application of cell therapy.

Effect of needle diameter on the viability of equine bone marrow derived mesenchymal stem cells

OBJECTIVES

Mesenchymal stem cells (MSCs) are frequently delivered via needle injection for treatment of musculoskeletal injuries. The purpose of this study was to evaluate the effect of needle diameter on the viability of MSCs.

METHODS

Equine bone marrow-derived MSCs from 5 horses were suspended in PBS, and held at room temperature for 7 hours to mimic shipping conditions. Two replicate samples for each needle size (20, 22, 23, or 25-gauge [ga]) were aspirated into a 3 mL syringe and re-injected into the holding vial 3 times, to reproduce the resuspension of cells prior to injection in clinical cases. Cells were stained with fluorescein diacetate and propidium iodide to measure viability. Flow cytometry (FC) was performed to compare cell debris and intact cells between groups.

RESULTS

MSC viability was higher when cells were passed through a 20-ga rather than a 25-ga needle. Cell suspensions passed through a 20-ga needle contained a larger percentage of intact cells, compared to 25-ga samples. The percentage of debris present in cell suspensions tended to increase with decreasing needle diameter. Neither horse nor passage had a significant effect on viability.

CONCLUSIONS

Cell damage is more likely when MSCs are passed through 25-ga rather than 20-ga needles.

CLINICAL RELEVANCE

Use of needles larger than 25-ga is recommended to maintain the viability of MSCs injected in horses.

Response to Intravenous Allogeneic Equine Cord Blood-Derived Mesenchymal Stromal Cells Administered from Chilled or Frozen State in Serum and Protein-Free Media

Equine mesenchymal stromal cells (MSC) are commonly transported, chilled or frozen, to veterinary clinics. These MSC must remain viable and minimally affected by culture, transport, or injection processes. The safety of two carrier solutions developed for optimal viability and excipient use were evaluated in ponies, with and without allogeneic cord blood-derived (CB) MSC. We hypothesized that neither the carrier solutions nor CB-MSC would elicit measurable changes in clinical, hematological, or biochemical parameters. In nine ponies (study 1), a bolus of HypoThermosol^® FRS (HTS-FRS), CryoStor^® CS10 (CS10), or saline was injected IV (n = 3/treatment). Study 2, following a 1-week washout period, 5 × 10⁷ pooled allogeneic CB-MSCs were administered IV in HTS-FRS following 24 h simulated chilled transport. Study 3, following another 1-week washout period 5 × 10⁷ pooled allogeneic CB-MSCs were administered IV in CS10 immediately after thawing. Nine ponies received CB-MSCs in study 2 and 3, and three ponies received the cell carrier media without cells. CB-MSCs were pooled in equal numbers from five unrelated donors. In all studies, ponies were monitored with physical examination, and blood collection for 7 days following injection. CD4 and CD8 lymphocyte populations were also evaluated in each blood sample. In all three studies, physical exam, complete blood cell count, serum biochemistry, and coagulation panel did not deviate from established normal ranges. Proportions of CD4⁺ and CD8⁺ lymphocytes increased at 168 h postinjection in CB-MSC treatment groups regardless of the carrier solution. Decreases in CD4^+/CD8⁺ double positive populations were observed at 24 and 72 h in CB-MSC-treated animals. There was no difference in viability between CB-MSCs suspended in HTS-FRS and CS10. HTS-FRS and CS10 used for low volume excipient injection of MSC suspensions were not associated with short-term adverse reactions. HTS-FRS and CS10 both adequately maintain CB-MSC viability following hypothermic or frozen simulated transport, respectively. CB-MSCs do not elicit clinical abnormalities, but allogeneic stimulation of CD4⁺ and CD8⁺ lymphocyte populations may occur. Future studies should include in vitro or in vivo evaluation of cell-mediated or adaptive immunity to autologous, identical allogeneic, or MSC originating from additional unrelated individuals in order to better characterize this response.

Stem Cell Delivery With Polymer Hydrogel for Treatment of Intervertebral Disc Degeneration: From 3D Culture to Design of the Delivery Device for Minimally Invasive Therapy

Nucleus pulposus (NP) tissue damage can induce detrimental mechanical strain on the biomechanical performance of intervertebral discs (IVDs), causing subsequent disc degeneration. A novel, photocurable, injectable, synthetic polymer hydrogel (pHEMA-co-APMA grafted with PAA) has already demonstrated success in encapsulating and differentiating human mesenchymal stem cells (hMSCs) toward an NP phenotype during hypoxic conditions. After demonstration of promising results in our previous work, in this study we have further investigated the inclusion of mechanical stimulation and its impact on hMSC differentiation toward an NP phenotype through the characterization of matrix markers such as SOX-9, aggrecan, and collagen II. Furthermore, investigations were undertaken in order to approximate delivery parameters for an injection delivery device, which could be used to transport hMSCs suspended in hydrogel into the IVD. hMSC-laden hydrogel solutions were injected through various needle gauge sizes in order to determine its impact on postinjection cell viability and IVD tissue penetration. Interpretation of these data informed the design of a potential minimally invasive injection device, which could successfully inject hMSCs encapsulated in a UV-curable polymer into NP, prior to photo-cross-linking in situ.

Advances in the Use of Stem Cells in Veterinary Medicine: From Basic Research to Clinical Practice

Today, several veterinary diseases may be treated with the administration of stem cells. This is possible because these cells present a high therapeutic potential and may be injected as autologous or allogenic, freshly isolated, or previously cultured. The literature supports that the process is safe and brings considerable benefits to animal health. Knowledge about how adult stem cells modulate the molecular signals to activate cell homing has also been increasingly determined, evidencing the mechanisms which enable cells to repair and regenerate injured tissues. Preclinical studies were designed for many animal models and they have contributed to the translation to the human clinic. This review shows the most commonly used stem cell types, with emphasis on mesenchymal stem cells and their mechanistic potential to repair, as well as the experimental protocols, studied diseases, and species with the highest amount of studies and applications. The relationship between stem cell protocols utilized on clinics, molecular mechanisms, and the physiological responses may offer subsidies to new studies and therefore improve the therapeutic outcome for both humans and animals.

Evaluation of transport conditions for autologous bone marrow-derived mesenchymal stromal cells for therapeutic application in horses

Background. Mesenchymal stromal cells (MSCs) are increasingly used for clinical applications in equine patients. For MSC isolation and expansion, a laboratory step is mandatory, after which the cells are sent back to the attending veterinarian. Preserving the biological properties of MSCs during this transport is paramount. The goal of the study was to compare transport-related parameters (transport container, media, temperature, time, cell concentration) that potentially influence characteristics of culture expanded equine MSCs.

Methods. The study was arranged in three parts comparing (I) five different transport containers (cryotube, two types of plastic syringes, glass syringe, CellSeal), (II) seven different transport media, four temperatures (4 °C vs. room temperature; −20 °C vs. −80 °C), four time frames (24 h vs. 48 h; 48 h vs. 72 h), and (III) three MSC concentrations (5 × 10⁶, 10 × 10⁶, 20 × 10⁶ MSC/ml). Cell viability (Trypan Blue exclusion; percent and total number viable cell), proliferation and trilineage differentiation capacity were assessed for each test condition. Further, the recovered volume of the suspension was determined in part I. Each condition was evaluated using samples of six horses (n = 6) and differentiation protocols were performed in duplicates.

Results. In part I of the study, no significant differences in any of the parameters were found when comparing transport containers at room temperature. The glass syringe was selected for all subsequent evaluations (highest recoverable volume of cell suspension and cell viability). In part II, media, temperatures, or time frames had also no significant influence on cell viability, likely due to the large number of comparisons and small sample size. Highest cell viability was observed using autologous bone marrow supernatant as transport medium, and “transport” at 4 °C for 24 h (70.6% vs. control group 75.3%); this was not significant. Contrary, viability was unacceptably low (<40%) for all freezing protocols at −20 °C or −80 °C, particularly with bone marrow supernatant or plasma and DMSO. In part III, various cell concentrations also had no significant influence on any of the evaluated parameters. Chondrogenic differentiation showed a trend towards being decreased for all transport conditions, compared to control cells.

Discussion. In this study, transport conditions were not found to impact viability, proliferation or ability for trilineage differentiation of MSCs, most likely due to the small sample size and large number of comparisons. The unusual low viability after all freezing protocols is in contrast to previous equine studies. Potential causes are differences in the freezing, but also in thawing method. Also, the selected container (glass syringe) may have impacted viability. Future research may be warranted into the possibly negative effect of transport on chondrogenic differentiation.

Aspiration, but not injection, decreases cultured equine mesenchymal stromal cell viability

Background

Recently, equine multipotent mesenchymal stromal cells (MSC) have received significant attention as therapy for various conditions due to their proposed regenerative and immune-modulating capacity. MSC are commonly administered to the patient through a hypodermic needle. Currently, little information is available on the effect of such injection has on equine MSC immediate and delayed viability. We hypothesize that viability of equine MSC is not correlated with needle diameter during aspiration and injection.

Results

Using a 3 mL syringe, manual injection of equine cord blood (CB) or bone marrow-derived (BM) MSC with no needle and needles ranging in size from 18 to 30 Ga did not affect immediate MSC viability. Similarly, 24 h post-injection, MSC delayed viability was not different between any of the tested needles as determined by a resazurin-based proliferation assay. Using a 3 mL syringe, aspiration of MSC through 20, 25, and 30 Ga needles resulted in significant decreases in immediate viability with no change in delayed viability when compared to aspiration without a needle. BM- and CB-MSC were observed to be of similar size with a diameter ± SD of 19.8 ± 2.7 and 20.4 ± 2.2 μm, respectively. In comparison, the smallest needles, (30 Ga) have an internal diameter of 160 μm.

Conclusions

Following injection, needle diameter did not affect immediate or delayed viability of equine MSC. Following aspiration through needles sizes 20 Ga and smaller, immediate viability, but not delayed viability, decreased. As a result, an 18 Ga or larger needle should be utilized for aspiration of cell suspensions. In contrast, needle selection for MSC injection should be based on clinical preference and experience rather than concerns over decreasing MSC viability.

Human Adipose-Derived Mesenchymal Stromal/Stem Cells Remain Viable and Metabolically Active Following Needle Passage

OBJECTIVE

To assess the biological effects of passage through clinically relevant needles on the viability and metabolic activity of culture-expanded, human adipose tissue-derived mesenchymal stromal/stem cells (AMSCs).

DESIGN

Prospective observational pilot study.

SETTING

Academic medical center.

PARTICIPANTS

Patient-derived clinical-grade culture expanded AMSCs.

INTERVENTIONS

AMSCs were passed through syringes without a needle attached (control), with an 18-gauge (25.4-mm) needle attached and with a 30-gauge (19-mm) needle attached at a constant injection flow rate and constant cell concentrations. Each injection condition was completed in triplicate.

MAIN OUTCOME MEASURES

Cell number and viability, proliferative capacity, metabolic activity, and acute gene expression as measured by cell counts, mitochondrial activity, and quantitative real time reverse-transcription polymerase chain reaction on day 0 (immediately), day 1, and day 4 after injection.

RESULTS

AMSC viability was not significantly affected by injection, and cells proliferated normally regardless of study group. Postinjection, AMSCs robustly expressed both proliferation markers and extracellular matrix proteins. Stress-response mRNAs were markedly but transiently increased independently of needle size within the first day in culture postinjection.

CONCLUSIONS

Human, culture-expanded AMSCs maintain their viability, proliferative capacity, and metabolic function following passage through needles as small as 30-gauge at constant flow rates of 4 mL/min, despite an early, nonspecific stress/cytoprotective response. These initial findings suggest that culture-expanded AMSCs should tolerate the injection process during most cell-based therapeutic interventions.

Cryopreservation of equine mesenchymal stem cells in 95% autologous serum and 5% DMSO does not alter post-thaw growth or morphology in vitro compared to fetal bovine serum or allogeneic serum at 20 or 95% and DMSO at 10 or 5

Introduction

Equine superficial digital flexor tendon injury is a well-accepted model of human tendon injury and is routinely treated with local injections of autologous mesenchymal stem cells (MSCs). Identification of a clinically safe medium for short-term cryopreservation of MSCs prior to cell implantation would streamline laboratory and clinical procedures for autologous regenerative therapies. Veterinary experience with short-term (MSCs prepared after the injury has occurred) cryopreserved MSCs in naturally occurring injury in the horse will be of value to human practitioners.

Methods

Equine bone marrow derived MSCs were cryopreserved in 6 different solutions consisting of 20 % serum, 10 % DMSO and 70 % media or 95 % serum and 5 % DMSO. Serum was autologous serum, commercially available pooled equine serum or fetal bovine serum (FBS). Cell survival, morphology and growth kinetics were assessed by total cell number, measurement of growth kinetics, colony-forming-unit-assay and morphology of MSCs after monolayer culture post-thaw.

Results

There were no significant differences in post-thaw viability, total cell number, morphology scores or growth kinetics among the 6 solutions. Post thaw viabilities from each group ranged from 80-90 %. In all solutions, there were significantly fewer MSCs and the majority (99 %) of MSCs remained in the original generation 24 hours post-thaw. Seventy two hours post-thaw, the majority of MSCs (50 %) were proliferating in the fourth generation. Mean colony count in the CFU-F assay ranged from 72 to 115 colonies.

Conclusions

Each of the serum sources could be used for short-term cryopreservation of equine bone marrow derived MSCs. Prior to clinical use, clinicians may prefer autologous serum and a lower concentration of DMSO.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0230-y) contains supplementary material, which is available to authorized users.