Cryostorage of Mesenchymal Stem Cells and Biomedical Cell-Based Products

Clinical experience with cryopreserved mesenchymal stem cells for cardiovascular applications: A systematic review

BACKGROUND

As living biodrugs, mesenchymal stem cells (MSCs) have progressed to phase 3 clinical trials for cardiovascular applications. However, their limited immediate availability hampers their routine clinical use.

AIM

To validate our hypothesis that cryopreserved MSCs (CryoMSCs) are as safe and effective as freshly cultured MSC counterparts but carry logistical advantages.

METHODS

Four databases were systematically reviewed for relevant randomized controlled trials (RCTs) evaluating the safety and efficacy of CryoMSCs from various tissue sources in treating patients with heart disease. A subgroup analysis was performed based on MSC source and post-thaw cell viability to determine treatment effects across different CryoMSCs sources and viability status. Weighted mean differences (WMDs) and odds ratios were calculated to measure changes in the estimated treatment effects. All statistical analyses were performed using RevMan version 5.4.1 software.

RESULTS

Seven RCTs (285 patients) met the eligibility criteria for inclusion in the meta-analysis. During short-term follow-up, CryoMSCs demonstrated a significant 2.11% improvement in left ventricular ejection fraction (LVEF) [WMD (95%CI) = 2.11 (0.66-3.56), P = 0.004, I 2 = 1%], with umbilical cord-derived MSCs being the most effective cell type. However, the significant effect on LVEF was not sustained over the 12 months of follow-up. Subgroup analysis demonstrated a substantial 3.44% improvement in LVEF [WMD (95%CI) = 3.44 (1.46-5.43), P = 0.0007, I 2 = 0%] when using MSCs with post-thaw viability exceeding 80%. There was no statistically significant difference in the frequency of major cardiac adverse events observed in rehospitalization or mortality in patients treated with CryoMSCs vs the control group.

CONCLUSION

CryoMSCs are a promising option for heart failure patients, particularly considering the current treatment options for cardiovascular diseases. Our data suggest that CryoMSCs could be a viable alternative or complementary treatment to the current options, potentially improving patient outcomes.

Functional characterization and therapeutic potential of human umbilical cord blood mononuclear cells

Human umbilical cord blood mononuclear cells (hUCB-MNCs) are a population of cells derived from neonatal cord blood, encompassing various stem cells and immune cells. The unique characteristics of hUCB-MNCs endow them with distinctive multifunctionality, including the promotion of angiogenesis, acceleration of tissue repair, regulation of immune responses, neuroprotection, alleviation of inflammatory reactions, enhancement of antioxidant capacity, reduction of fibrosis processes, and inhibition of apoptosis. These diverse biological properties underscore the significant clinical therapeutic potential of hUCB-MNCs, which are widely applied in the treatment of various diseases. This review aims to summarize the underlying mechanisms responsible for the multifunctional attributes of hUCB-MNCs, elucidating their potential modes of action in disease management and providing novel theoretical insights and practical guidance for their expanded application across different disease domains. By synthesizing current research findings, this review may provide insights into the potential clinical applications of hUCB-MNCs in the fields of regenerative medicine and cell therapy.

Vitrification of 3D-MSCs encapsulated in GelMA hydrogel: Improved cryosurvival, reduced cryoprotectant concentration, and enhanced wound healing

Compared to traditional 2D-cultured mesenchymal stem cells (MSCs), 3D-MSCs offer distinct advantages in disease treatment. However, large-scale culture of 3D-MSCs remains labor-intensive and time-consuming. Thus, developing cryopreservation method for 3D-MSCs is essential for clinical application. Existing cryopreservation techniques primarily focus on 2D-cultured MSCs, and vitrification methods such as Cryotop are not suitable for large-scale applications, often leading to cytotoxicity due to high concentrations of cryoprotective agents. To address these challenges, we developed an innovative vitrification method using microfluidics, which involved encapsulating 3D human umbilical cord MSCs in GelMA hydrogel to create 3D-MSCs hydrogel microspheres (3D-MSCsHM). This approach significantly enhanced the survival rates of MSCs while reducing the need for cryoprotective agents. The entire process could be completed in 30 min, yielding 96 % viability and functionality upon rewarming. Proteomic analysis further revealed that improved viability and functions post rewarming were linked to enhance mitochondrial function, increased antioxidant proteins, and elevated growth factors. Furthermore, this method showed effective therapeutic outcomes in wound healing in a mouse model, comparable to those achieved with fresh 3D-MSCs. The presented vitrification technique offers a practical solution for the cryopreservation of multicellular stem cell tissues, enhancing their therapeutic applications.

Regenerative effect of lyophilized dental follicle mesenchymal stem cells and platelet-rich fibrin in skin wounds in geriatric and young rats

The aim of this study was to investigate the regenerative effect of lyophilized dental follicle mesenchymal stem cells (DF-MSCs) combined with rat platelet-rich fibrin (PRF) on geriatric skin wounds. Human DF-MSCs which were isolated from the wisdom teeth of healthy donors and PRF were mixed and incubated in a 37 °C incubator for 1-2 h containing 1 million cells in 150 mg PRF. The mixture was suspended in a freeze-drying solution and then lyophilized. Wounds were created on the back skin of Wistar albino rats using a 6 mm punch. Lyophilized DF-MSCs, PRF, or PRF + DF-MSCs were applied to the wounds of rats. On the 15th day, the wound area was histopathologically evaluated in rats. Blood samples from rats were analyzed for total antioxidant status (TAOS), and inflammatory cytokine levels using ELISA. In both young and geriatric rats treated with lyophilized PRF + DF-MSCs, wound area began to significantly decrease from the 10th day compared to the untreated group (p < 0.05). Histopathological examination revealed that in the lyophilized PRF + DF-MSCs treated groups, epithelial integrity and scarless healing significantly increased compared to the untreated groups (p < 0.05). There were no significant differences in TAOS, total oxidant status (TOS), tumor necrosis factor (TNF), interleukin-6 (IL6), and hydroxyproline levels in serum samples from young rats on the 15th day. In geriatric rats, hydroxyproline (HYPS) levels were increased in the DF-MSC and PRF + DF-MSC groups (p < 0.01), TNF was significantly elevated in PRF geriatric group and IL6 was increased in the PRF group compared to the control group (p = 0.01). Lyophilized PRF + DF-MSCs, which is a shelf-stable and ready-to-use product, hold promise, especially for traumatic wounds in geriatric individuals with longer healing times.

Automated Manufacturing Processes and Platforms for Large-scale Production of Clinical-grade Mesenchymal Stem/ Stromal Cells

Mesenchymal stem/stromal cells (MSCs) hold immense potential for regenerative medicine due to their remarkable regenerative and immunomodulatory properties. However, their therapeutic application requires large-scale production under stringent regulatory standards and Good Manufacturing Practice (GMP) guidelines, presenting significant challenges. This review comprehensively evaluates automated manufacturing processes and platforms for the scalable production of clinical-grade MSCs. Various large-scale culture vessels, including multilayer flasks and bioreactors, are analyzed for their efficacy in MSCs expansion. Furthermore, automated MSCs production platforms, such as Quantum® Cell Expansion System, CliniMACS Prodigy®, NANT001/ XL, CellQualia™, Cocoon® Platform, and Xuri™ Cell Expansion System W25 are reviewed and compared as well. We also underscore the importance of optimizing culture media specifically emphasizing the shift from fetal bovine serum to humanized or serum-free alternatives to meet GMP standards. Moreover, advances in alternative cryopreservation methods and controlled-rate freezing systems, that offer promising improvements in MSCs preservation, are discussed as well. In conclusion, advancing automated manufacturing processes and platforms is essential for realizing the full potential of MSCs-based regenerative medicine and accomplishing the increasing demand for cell-based therapies. Collaborative initiatives involving industry, academia, and regulatory bodies are emphasized to accelerate the translation of MSCs-based therapies into clinical practice.

Evaluating the potential of off-the-shelf engineered mesenchymal stem cells for targeted Hepatocellular Carcinoma treatment: A multisite proof-of-concept study

Although combining 5-fluorouracil (5-FU) and Interferon-beta (IFNb) improves response rates in Hepatocellular Carcinoma (HCC), the outcomes remain suboptimal. This study investigates the feasibility of using highly transfected Mesenchymal Stem Cells (MSCs) to deliver a chemotherapeutic (5-FU) and an immunomodulator (IFNb) for localized HCC treatment. Considering the crucial role of cold-chain transportation in off-the-shelf allogeneic therapy, the study also assesses the quality and efficacy of frozen-thawed engineered MSCs, simulating a multisite study process. The engineered MSCs maintained their phenotypes and tumour tropism. With just 10 % engineered MSCs, a killing efficiency of over 70 % was achieved in Huh-7 and HepG2 cell lines in vitro. Coculture studies, soft agar assays, and in vivo experiments confirmed that MSCs are neither tumorigenic nor tumour-promoting. Tumour mass growth was inhibited by >80 % in the treated mice group. TUNEL, Annexin-V, and Ki67 staining confirmed DNA damage, cell death, and proliferation inhibition post-treatment. Blood chemistry and the weight of the mice were comparable to the control group, indicating a good safety profile. This proof-of-concept study demonstrates the efficacy and safety of off-the-shelf CDUPRT-IFNβ_MSCs in targeting hepatocellular carcinoma (HCC) growth. Evaluating the complete value chain of MSC therapy in early-stage preclinical studies is essential for justifying further investigation and clinical translation of this cell product.

Cryopreservation of mesenchymal stem/stromal cells using a DMSO-free solution is comparable to DMSO-containing cryoprotectants: results of an international multicenter PACT/BEST collaborative study

BACKGROUND AND AIM

An essential aspect of ensuring availability and stability of mesenchymal stem/stromal cells (MSCs) products for clinical use is that these cells are cryopreserved before individual infusion into patients. Currently, cryopreservation of MSCs involves use of a cryoprotectant solution containing dimethyl sulfoxide (DMSO). However, it is recognized that DMSO may be toxic for both the patient and the MSC product. In this Production Assistance for Cellular Therapies (PACT) and Biomedical Excellence for Safer Transfusion (BEST) Collaborative study, we compared a novel DMSO-free solution with DMSO containing cryoprotectant solutions for freezing MSCs.

METHODS

A DMSO-free cryoprotectant solution containing sucrose, glycerol, and isoleucine (SGI) in a base of Plasmalyte A was prepared at the University of Minnesota. Cryoprotectant solutions containing 5-10% DMSO (in-house) were prepared at seven participating centers (five from USA, one each from Australia and Germany). The MSCs were isolated from bone marrow or adipose tissue and cultured ex vivo per local protocols at each center. The cells in suspension were frozen by aliquoting into vials/bags. For six out of the seven centers, the vials/bags were placed in a controlled rate freezer (one center placed them at -80°C freezer overnight) before transferring to liquid nitrogen. The cells were kept frozen for at least one week before thawing and testing. Pre- and post-thaw assessment included cell viability and recovery, immunophenotype as well as transcriptional and gene expression profiles. Linear regression, mixed effects models and two-sided t-tests were applied for statistical analysis.

RESULTS

MSCs had an average viability of 94.3% (95% CI: 87.2-100%) before cryopreservation, decreasing by 4.5% (95% CI: 0.03-9.0%; P: 0.049) and 11.4% (95% CI: 6.9-15.8%; P< 0.001), for MSCs cryopreserved in the in-house and SGI solutions, respectively. The average recovery of viable MSCs cryopreserved in the SGI was 92.9% (95% CI: 85.7-100.0%), and it was lower by 5.6% (95% CI: 1.3-9.8%, P < 0.013) for the in-house solution. Additionally, MSCs cryopreserved in the two solutions had expected level of expressions for CD45, CD73, CD90, and CD105 with no significant difference in global gene expression profiles.

CONCLUSION

MSCs cryopreserved in a DMSO-free solution containing sucrose, glycerol, and isoleucine in a base of Plasmalyte A had slightly lower cell viability, better recovery, and comparable immunophenotype and global gene expression profiles compared to MSCs cryopreserved in DMSO containing solutions. The average viability of MSCs in the novel solution was above 80% and, thus, likely clinically acceptable. Future studies are suggested to test the post-thaw functions of MSCs cryopreserved in the novel DMSO-free solution.

Cryopreservation of Neuroectoderm on a Pillar Plate and In Situ Differentiation into Human Brain Organoids

Cryopreservation in cryovials extends cell storage at low temperatures, and advances in organoid cryopreservation improve reproducibility and reduce generation time. However, cryopreserving human organoids presents challenges due to the limited diffusion of cryoprotective agents (CPAs) into the organoid core and the potential toxicity of these agents. To overcome these obstacles, we developed a cryopreservation technique using a pillar plate platform. To demonstrate cryopreservation application to human brain organoids (HBOs), early stage HBOs were produced by differentiating induced pluripotent stem cells (iPSCs) into neuroectoderm (NE) in an ultralow attachment (ULA) 384-well plate. The NE was transferred and encapsulated in Matrigel on the pillar plate. The NE on the pillar plate was exposed to four commercially available CPAs, including the PSC cryopreservation kit, CryoStor CS10, 3dGRO, and 10% DMSO, before being frozen overnight at -80 °C and subsequently stored in a liquid nitrogen dewar. We examined the impact of the CPA type, organoid size, and CPA exposure duration on cell viability post-thaw. Additionally, the differentiation of NE into HBOs on the pillar plate was assessed using RT-qPCR and immunofluorescence staining. The PSC cryopreservation kit proved to be the least toxic for preserving the early stage HBOs on the pillar plate. Notably, smaller HBOs showed higher cell viability postcryopreservation than larger ones. An incubation period of 80 min with the PSC kit was essential to ensure optimal CPA diffusion into HBOs with a diameter of 400-600 μm. These cryopreserved early stage HBOs successfully matured over 30 days, exhibiting gene expression patterns akin to noncryopreserved HBOs. The cryopreserved early stage HBOs on the pillar plate maintained high viability after thawing and successfully differentiated into mature HBOs. This on-chip cryopreservation method could extend to other small organoids, by integrating cryopreservation, thawing, culturing, staining, rinsing, and imaging processes within a single system, thereby preserving the 3D structure of the organoids.

Optimisation of cryopreservation conditions, including storage duration and revival methods, for the viability of human primary cells

BACKGROUND

Cryopreservation is a crucial procedure for safeguarding cells or other biological constructs, showcasing considerable potential for applications in tissue engineering and regenerative medicine.

AIMS

This study aimed to evaluate the effectiveness of different cryopreservation conditions on human cells viability.

METHODS

A set of cryopreserved data from Department of Tissue Engineering and Regenerative Medicine (DTERM) cell bank were analyse for cells attachment after 24 h being revived. The revived cells were analysed based on different cryopreservation conditions which includes cell types (skin keratinocytes and fibroblasts, respiratory epithelial, bone marrow mesenchymal stem cell (MSC); cryo mediums (FBS + 10% DMSO; commercial medium); storage durations (0 to > 24 months) and locations (tank 1-2; box 1-5), and revival methods (direct; indirect methods). Human dermal fibroblasts (HDF) were then cultured, cryopreserved in different cryo mediums (HPL + 10% DMSO; FBS + 10% DMSO; Cryostor) and stored for 1 and 3 months. The HDFs were revived using either direct or indirect method and cell number, viability and protein expression analysis were compared.

RESULTS

In the analysis cell cryopreserved data; fibroblast cells; FBS + 10% DMSO cryo medium; storage duration of 0-6 months; direct cell revival; storage in vapor phase of cryo tank; had the highest number of vials with optimal cell attachment after 24 h revived. HDFs cryopreserved in FBS + 10% DMSO for 1 and 3 months with both revival methods, showed optimal live cell numbers and viability above 80%, higher than other cryo medium groups. Morphologically, the fibroblasts were able to retain their phenotype with positive expression of Ki67 and Col-1. HDFs cryopreserved in FBS + 10% DMSO at 3 months showed significantly higher expression of Ki67 (97.3% ± 4.62) with the indirect revival method, while Col-1 expression (100%) was significantly higher at both 1 and 3 months compared to other groups.

CONCLUSION

In conclusion, fibroblasts were able to retain their characteristics after various cryopreservation conditions with a slight decrease in viability that may be due to the thermal-cycling effect. However, further investigation on the longer cryopreservation periods should be conducted for other types of cells and cryo mediums to achieve optimal cryopreservation outcomes.

Exploring the Potential Effects of Cryopreservation on the Biological Characteristics and Cardiomyogenic Differentiation of Rat Adipose-Derived Mesenchymal Stem Cells

Cryopreservation is essential for the broad clinical application of mesenchymal stem cells (MSCs), yet its impact on their cellular characteristics and cardiomyogenic differentiation potential remains a critical concern in translational medicine. This study aimed to evaluate the effects of cryopreservation on the biological properties and cardiomyogenic capacity of rat adipose-derived MSCs (AD-MSCs). We examined their cellular morphology, surface marker expression (CD29, CD90, CD45), trilineage differentiation potential (adipogenic, osteogenic, chondrogenic), and gene expression profiles for the pluripotency marker REX1 and immunomodulatory markers TGFβ1 and IL-6. After inducing cardiomyocyte differentiation, we assessed cardiac-specific gene expressions (Troponin I, MEF2c, GSK-3β) using quantitative RT-qPCR, along with live/dead cell staining and immunofluorescence for cardiac-specific proteins (Troponin T, α-actinin, Myosin Heavy Chain). Cryopreserved AD-MSCs preserved their morphology, surface markers, and differentiation potential, but exhibited a reduced expression of REX1, TGFβ1, and IL-6. Additionally, cryopreservation diminished cardiomyogenic differentiation, as indicated by the lower levels of Troponin I, MEF2c, and GSK-3β seen compared to non-cryopreserved cells. Despite this, high cell viability (>90%) and maintained cardiac protein expression were observed post-cryopreservation. These findings highlight the necessity of optimizing cryopreservation protocols to ensure the full therapeutic potential of AD-MSCs, particularly in applications related to cardiac regenerative medicine.

Key quality parameter comparison of mesenchymal stem cell product cryopreserved in different cryopreservation solutions for clinical applications

Introduction

Cryopreservation is a critical process of cell products for achieving a commercial viability through wide scale adoption. By preserving cells in a lower temperature, cryopreservation enables a product to be off-the-shelf and ready for infusion. An optimized cryopreservation strategy can maintain the viability, phenotype, and potency of thawed mesenchymal stromal/stem cells (MSCs) while being regulatory compliant. We compared three clinical-ready formulations with one research cryopreservation solutions and evaluated key quality parameters of post thawed MSCs.

Method and result

MSCs were cryopreserved at 3, 6, and 9 million cells/mL (M/mL) in four different cryopreservation solutions: NutriFreez (10% dimethyl sulfoxide [DMSO]), Plasmalyte A (PLA)/5% human albumin (HA)/10% DMSO (PHD10), CryoStor CS5 (5% DMSO), and CryoStor CS10 (10% DMSO). To establish post thaw viability, cells were evaluated with no dilution of DMSO (from 3 M/mL), 1:1 dilution (from 6 M/mL), or 1:2 dilution (from 9 M/mL) with PLA/5% HA, to achieve uniform concentration at 3 M/mL. Cell viability was measured at 0-, 2-, 4-, and 6-h post thaw with Trypan blue exclusion and Annexin V/PI staining. Dilution (1:2) of final cell products from 9M/mL resulted in an improvement of cell viability over 6 h but showed a trend of decreased recovery. MSCs cryopreserved in solutions with 10% DMSO displayed comparable viabilities and recoveries up to 6 h after thawing, whereas a decreasing trend was noted in cell viability and recovery with CS5. Cells from all groups exhibited surface marker characteristics of MSCs. We further evaluated cell proliferation after 6-day recovery in culture. While cells cryopreserved in NutriFreez and PHD10 presented similar cell growth post thaw, MSCs cryopreserved in CS5 and CS10 at 3 M/mL and 6M/mL showed 10-fold less proliferative capacity. No significant differences were observed between MSCs cryopreserved in NutriFreez and PHD10 in their potency to inhibit T cell proliferation and improve monocytic phagocytosis.

Conclusion

MSCs can be cryopreserved up to 9 M/mL without losing notable viability and recovery, while exhibiting comparable post thaw potency with NutriFreez and PHD10. These results highlight the importance of key parameter testing for selecting the optimal cryopreservation solution for MSC-based therapy.

Cryopreservation of neuroectoderm on a pillar plate and in situ differentiation into human brain organoids

Cryopreservation in cryovials extends cell storage at low temperatures, and advances in organoid cryopreservation improve reproducibility and reduce generation time. However, cryopreserving human organoids presents challenges due to the limited diffusion of cryoprotective agents (CPAs) into the organoid core and the potential toxicity of these agents. To overcome these obstacles, we developed a cryopreservation technique using a pillar plate platform. To illustrate cryopreservation application to human brain organoids (HBOs), early-stage HBOs were produced by differentiating induced pluripotent stem cells (iPSCs) into neuroectoderm (NEs) in an ultralow atachement (ULA) 384-well plate. These NEs were transferred and encapsulated in Matrigel on the pillar plate. The early-stage HBOs on the pillar plate were exposed to four commercially available CPAs, including PSC cryopreservation kit, CryoStor CS10, 3dGRO, and 10% DMSO, before being frozen overnight at -80°C and subsequently stored in a liquid nitrogen dewar. We examined the impact of CPA type, organoid size, and CPA exposure duration on cell viability post-thaw. Additionally, the differentiation of early-stage HBOs on the pillar plate was assessed using RT-qPCR and immunofluorescence staining. The PSC cryopreservation kit proved to be the least toxic for preserving these HBOs on the pillar plate. Notably, smaller HBOs showed higher cell viability post-cryopreservation than larger ones. An incubation period of 80 minutes with the PSC kit was essential to ensure optimal CPA diffusion into HBOs with a diameter of 400 - 600 μm. These cryopreserved early-stage HBOs successfully matured over 30 days, exhibiting gene expression patterns akin to non-cryopreserved HBOs. The cryopreserved early-stage HBOs on the pillar plate maintained high viability after thawing and successfully differentiated into mature HBOs. This on-chip cryopreservation method could extend to other small organoids, by integrating cryopreservation, thawing, culturing, staining, rinsing, and imaging processes within a single system, thereby preserving the 3D structure of the organoids.

Mesenchymal stem cells and their derived exosomes in multiple sclerosis disease: from paper to practice

Multiple sclerosis (MS) is a chronic neurodegenerative, inflammatory, and demyelinating disease of the central nervous system (CNS). Current medicines are not sufficient to control the inflammation and progressive damage to the CNS that is known in MS. These drawbacks highlight the need for novel treatment options. Cell therapy can now be used to treat complex diseases when conventional therapies are ineffective. Mesenchymal stem cells (MSCs) are a diverse group of multipotential non-hematopoietic stromal cells which have immunomodulatory, neurogenesis, and remyelinating capacity. Their advantageous effects mainly rely on paracrine, cell-cell communication and differentiation properties which introduced them as excellent candidates for MS therapy. Exosomes, as one of the MSCs secretomes, have unique properties that make them highly promising candidates for innovative approach in regenerative medicine. This review discusses the therapeutic potential of MSCs and their derived exosomes as a novel treatment for MS, highlighting the differences between these two approaches.

The Omentum-A Forgotten Structure in Veterinary Surgery in Small Animals' Surgery

The greater and lesser omentum are derived from embryonic mesogastrium. The expansive greater omentum in dogs covers intestinal coils, while in cats, it is smaller. Comprising distinct portions, the greater omentum is rich in lymphatics and blood vessels. Conversely, the lesser omentum spans the liver, stomach, and duodenum. Studies on canine omentum reveal unique immune cell composition and regenerative potential attributed to adipose tissue-derived stromal cells (ADSCs). These cells hold promise in regenerative medicine, showing enhanced abilities compared with ADSCs from other sources. The omentum is critical in tissue repair and pathology, making it invaluable in veterinary surgery across various medical fields. The aim of this article was to research current knowledge about the applications of the omentum in veterinary surgery and the possibilities of using this structure in the future.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects: Update from 2015 review

Mesenchymal stromal cells (MSCs) have become one of the most investigated and applied cells for cellular therapy and regenerative medicine. In this update of our review published in 2015, we show that studies continue to abound regarding the characterization of MSCs to distinguish them from other similar cell types, the discovery of new tissue sources of MSCs, and the confirmation of their properties and functions that render them suitable as a therapeutic. Because cryopreservation is widely recognized as the only technology that would enable the on-demand availability of MSCs, here we show that although the traditional method of cryopreserving cells by slow cooling in the presence of 10% dimethyl sulfoxide (Me2SO) continues to be used by many, several novel MSC cryopreservation approaches have emerged. As in our previous review, we conclude from these recent reports that viable and functional MSCs from diverse tissues can be recovered after cryopreservation using a variety of cryoprotectants, freezing protocols, storage temperatures, and periods of storage. We also show that for logistical reasons there are now more studies devoted to the cryopreservation of tissues from which MSCs are derived. A new topic included in this review covers the application in COVID-19 of MSCs arising from their immunomodulatory and antiviral properties. Due to the inherent heterogeneity in MSC populations from different sources there is still no standardized procedure for their isolation, identification, functional characterization, cryopreservation, and route of administration, and not likely to be a "one-size-fits-all" approach in their applications in cell-based therapy and regenerative medicine.

Minimal criteria for reporting mesenchymal stem cells in veterinary regenerative medicine

The widespread application of mesenchymal stem cells (MSCs) in veterinary regenerative medicine highlights their promising therapeutic potential. However, the lack of standardized characterization and reporting practices across studies poses a significant challenge, compromising the assessment of their safety and efficacy. While criteria established for human MSCs serve as a foundation, the unique characteristics of animal-derived MSCs warrant updated guidelines tailored to veterinary medicine. A recent position statement outlining minimal reporting criteria for MSCs in veterinary research reflects efforts to address this need, aiming to enhance research quality and reproducibility. Standardized reporting criteria ensure transparency, facilitate evidence synthesis, and promote best practices adoption in MSC isolation, characterization, and administration. Adherence to minimal reporting criteria is crucial for maintaining scientific rigor and advancing the field of veterinary regenerative medicine. Ongoing collaboration among stakeholders is essential for effective implementation and adherence to updated guidelines, fostering excellence and innovation in MSC-based therapies for animal patients.

Long-Term Cryopreservation May Cause Genomic Instability and the Premature Senescence of Cells

Cryopreservation is an essential step for utilizing various cell types for biological research and medical purposes. At the same time, there is a lack of data on the effect of cryopreservation, especially when prolonged, on the karyotype of cells. In the present work, we analyzed the genetic stability of cells subjected to a cryopreservation procedure. The objects were immortalized Chinese hamster lung fibroblasts (CHL V-79 RJK line) and human endometrial mesenchymal stem/stromal cells (eMSCs). We showed that short-term cryopreservation in liquid nitrogen for up to 6 months did not affect the karyotype stability of CHL V-79 RJK and eMSCs. On the contrary, karyotyping of G-banded metaphase chromosomes in cells underwent 10-year cryopreservation, which revealed genomic instability in both cell lines associated with the variability of chromosome number in cells, random chromosomal rearrangements, and condensation disorder in homologs. In addition, we found out that long-term cryopreservation of eMSCs does not affect the expression of their typical surface markers and morphology, but results in a significant reduction in proliferative potential and early manifestation of cellular senescence features upon eMSCs culturing. Thus, we concluded that the long-term cryopreservation of cells of different types and biological origin can lead to irreversible changes of their karyotype and acceleration of cellular senescence.

Specifics of Cryopreservation of Hydrogel Biopolymer Scaffolds with Encapsulated Mesenchymal Stem Cells

The demand for regenerative medicine products is growing rapidly in clinical practice. Unfortunately, their use has certain limitations. One of these, which significantly constrains the widespread distribution and commercialization of such materials, is their short life span. For products containing suspensions of cells, this issue can be solved by using cryopreservation. However, this approach is rarely used for multicomponent tissue-engineered products due to the complexity of selecting appropriate cryopreservation protocols and the lack of established criteria for assessing the quality of such products once defrosted. Our research is aimed at developing a cryopreservation protocol for an original hydrogel scaffold with encapsulated MSCs and developing a set of criteria for assessing the quality of their functional activity in vitro. The scaffolds were frozen using two alternative types of cryocontainers and stored at either -40 °C or -80 °C. After cryopreservation, the external state of the scaffolds was evaluated in addition to recording the cell viability, visible changes during subsequent cultivation, and any alterations in proliferative and secretory activity. These observations were compared to those of scaffolds cultivated without cryopreservation. It was shown that cryopreservation at -80 °C in an appropriate type of cryocontainer was optimal for the hydrogels/adipose-derived stem cells (ASCs) tested if it provided a smooth temperature decrease during freezing over a period of at least three hours until the target values of the cryopreservation temperature regimen were reached. It was shown that evaluating a set of indicators, including the viability, the morphology, and the proliferative and secretory activity of the cells, enables the characterization of the quality of a tissue-engineered construct after its withdrawal from cryopreservation, as well as indicating the effectiveness of the cryopreservation protocol.

Comparison between Platelet Lysate, Platelet Lysate Serum, and Fetal Bovine Serum as Supplements for Cell Culture, Expansion, and Cryopreservation

As cell culture supplements, human platelet lysate (PL) and human platelet lysate serum (PLS) are alternatives to fetal bovine serum (FBS) due to FBS-related issues such as ethical concerns, variability between batches, and the possible introduction of xenogenic contaminants. This study compared the composition and efficacy of PL, PLS, and FBS as supplements in the culture and cryopreservation of human dermal fibroblasts, Wharton's jelly-derived mesenchymal stem cells (WJ-MCS), and adipose tissue (AdMSC). Biochemical components, some growth factors, and cytokines present in each of them were analyzed; in addition, the cells were cultured in media supplemented with 5% PL, 5% PLS, and 10% FBS and exposed to different freezing and thawing solutions with the supplements under study. Biochemical parameters were found to be similar in PL and PLS compared to FBS, with some differences in fibrinogen and calcium concentration. Growth factors and cytokines were higher in PL and PLS compared to FBS. Cell proliferation and morphology showed no significant differences between the three culture media. Regarding the cryopreservation and thawing of cells, better results were obtained with PLS and FBS. In conclusion, PL and PLS are an excellent choice to replace the standard supplement of animal origin (FBS) in the media used for the culture and cryopreservation of fibroblasts, WJ-MSC, and AdMSC.

Influence of the Anatomical Site on Adipose Tissue-Derived Stromal Cells' Biological Profile and Osteogenic Potential in Companion Animals

Adipose tissue-derived stromal cells (ADSCs) have generated considerable interest in the field of veterinary medicine, particularly for their potential in therapeutic strategies focused on bone regeneration. These cells possess unique biological characteristics, including their regenerative capacity and their ability to produce bioactive molecules. However, it is crucial to recognize that the characteristics of ADSCs can vary depending on the animal species and the site from which they are derived, such as the subcutaneous and visceral regions (SCAT and VAT, respectively). Thus, the present work aimed to comprehensively review the different traits of ADSCs isolated from diverse anatomical sites in companion animals, i.e., dogs, cats, and horses, in terms of immunophenotype, morphology, proliferation, and osteogenic differentiation potential. The findings indicate that the immunophenotype, proliferation, and osteogenic potential of ADSCs differ according to tissue origin and species. Generally, the proliferation rate is higher in VAT-derived ADSCs in dogs and horses, whereas in cats, the proliferation rate appears to be similar in both cells isolated from SCAT and VAT regions. In terms of osteogenic differentiation potential, VAT-derived ADSCs demonstrate the highest capability in cats, whereas SCAT-derived ADSCs exhibit superior potential in horses. Interestingly, in dogs, VAT-derived cells appear to have greater potential than those isolated from SCAT. Within the VAT, ADSCs derived from the falciform ligament and omentum show increased osteogenic potential, compared to cells isolated from other anatomical locations. Consequently, considering these disparities, optimizing isolation protocols becomes pivotal, tailoring them to the specific target species and therapeutic aims, and judiciously selecting the anatomical site for ADSC isolation. This approach holds promise to enhance the efficacy of ADSCs-based bone regenerative therapies.

Comparative Analysis of Biological Signatures between Freshly Preserved and Cryo-Preserved Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) can differentiate into multiple connective tissue lineages, including osteoblasts, chondrocytes, and adipocytes. MSCs secrete paracrine molecules that are associated with immunomodulation, anti-fibrotic effects, and angiogenesis. Due to their orchestrative potential, MSCs have been therapeutically applied for several diseases. An important aspect of this process is the delivery of high-quality MSCs to patients at the right time, and cryo-biology and cryo-preservation facilitate the advancement of the logistics thereof. This study aimed to compare the biological signatures between freshly preserved and cryo-preserved MSCs by using big data sourced from the Pharmicell database. From 2011 to 2022, data on approximately 2300 stem cell manufacturing cases were collected. The dataset included approximately 60 variables, including viability, population doubling time (PDT), immunophenotype, and soluble paracrine molecules. In the dataset, 671 cases with no missing data were able to receive approval from an Institutional Review Board and were analyzed. Among the 60 features included in the final dataset, 20 were selected by experts and abstracted into two features by using a principal component analysis. Circular clustering did not introduce any differences between the two MSC preservation methods. This pattern was also observed when using viability, cluster of differentiation (CD) markers, and paracrine molecular indices as inputs for unsupervised analysis. The individual average PDT and cell viability at most passages did not differ according to the preservation method. Most immunophenotypes (except for the CD14 marker) and paracrine molecules did not exhibit different mean levels or concentrations between the frozen and unfrozen MSC groups. Collectively, the biochemical signatures of the cryo-preserved and unfrozen bone marrow MSCs were comparable.

Banking of perinatal mesenchymal stem/stromal cells for stem cell-based personalized medicine over lifetime: Matters arising

Mesenchymal stromal/stem cells (MSCs) are currently applied in regenerative medicine and tissue engineering. Numerous clinical studies have indicated that MSCs from different tissue sources can provide therapeutic benefits for patients. MSCs derived from either human adult or perinatal tissues have their own unique advantages in their medical practices. Usually, clinical studies are conducted by using of cultured MSCs after thawing or short-term cryopreserved-then-thawed MSCs prior to administration for the treatment of a wide range of diseases and medical disorders. Currently, cryogenically banking perinatal MSCs for potential personalized medicine for later use in lifetime has raised growing interest in China as well as in many other countries. Meanwhile, this has led to questions regarding the availability, stability, consistency, multipotency, and therapeutic efficiency of the potential perinatal MSC-derived therapeutic products after long-term cryostorage. This opinion review does not minimize any therapeutic benefit of perinatal MSCs in many diseases after short-term cryopreservation. This article mainly describes what is known about banking perinatal MSCs in China and, importantly, it is to recognize the limitation and uncertainty of the perinatal MSCs stored in cryobanks for stem cell medical treatments in whole life. This article also provides several recommendations for banking of perinatal MSCs for potentially future personalized medicine, albeit it is impossible to anticipate whether the donor will benefit from banked MSCs during her/his lifetime.

The Evolving Landscape of Potency Assays

There is a "goldilocks" aspect to potency assays. On the one hand, a comprehensive evaluation of the cell product with detailed quantitative measurement of the critical quality attribute/s of the desired biological activity is required. On the other hand, the potency assay benefits from simplification and lean approaches that avoid unnecessary complication and enhance robustness, to provide a reproducible and scalable product. There is a need to balance insightful knowledge of complex biological healing processes with straightforward manufacture of an advanced therapeutic medicinal product (ATMP) that can be administered in a trustworthy cost-effective manner. While earlier chapters within this book have highlighted numerous challenges facing the potency assay conundrum, this chapter offers a forward-looking perspective regarding the many recent advances concerning acellular products, cryopreservation, induced MSC, cell priming, nanotechnology, 3D culture, regulatory guidelines and evolving institutional roles, that are likely to facilitate potency assay development in the future.

Survival of human cells in tissue-engineered constructs stored at room temperature

Tissue-engineered constructs (TECs), the dermal equivalent (DE) and the skin equivalent (SE), are allogenic equivalents of the skin and derm used to treat critical skin loss. Selection of storage conditions that contribute to longer shelf life, thereby expanding the possibilities of logistics and use, is one of the major issues related to the TECs development. The study was aimed to determine the shelf life of the DE and SE TECs stored in normal saline at room temperature by assessing morphology and viability of the cells on their surface, along with the levels of endothelial growth factor (VEGF) secreted by these cells. Using the MTT assay and staining with vital dye, we discovered the following: when TECs of both types were stored in normal saline, the cells viability and metabolic activity decreased by more than 50% by days 3–4 of storage. Furthermore, these decreased faster in DEs than in SEs. Morphology of the cells isolated from DEs and SEs after the 3-day storage remained unchanged. Mesenchymal stem cells on the surface of TECs kept producing VEGF after TECs culture medium was changed for saline solution (confirmed by immunofluorescence assay), which could indicate that the cells retained essential secretory activity.