Comparison of chloromethyl-dialkylcarbocyanine and green fluorescent protein for labeling human umbilical mesenchymal stem cells

Characterization of CM-Dil-labeled Muse cells in culture and in skin wounds in rats

To investigate the characteristics of multilineage-differentiating stress-enduring (Muse) cells labeled with chloromethyl dialkylcarbocyanine (CM-Dil) in culture and in skin wounds of rats. Normal human dermal fibroblasts (NHDFs) were obtained from foreskins and were confirmed by immunocytochemistry with vimentin. Muse cells were derived from NHDFs using long-term trypsinization (LTT), were confirmed using immunocytochemistry with antibodies against stage specific embryonic antigen-3 (SSEA-3) and CD105 and were expanded in suspension cultures. The Muse cells were labeled with CM-Dil and were further evaluated with respect to their biological properties using CCK-8 assays and scratch tests. One hundred µl CM-Dil-labeled Muse cells at a concentration of 5 × 103/µl were injected subcutaneously at the edges of skin wounds in adult male SD rats. At weeks 1, 3 and 5 after the injection, the distribution of CM-Dil-labeled Muse cells in skin tissues was observed using immunofluorescence microscopy. Muse cells were double-positive for CD105 and SSEA-3. ALP staining of the M-clusters were positive and they displayed orange-red fluorescence after labelling with CM-Dil, which had no adverse effects on their viability, migration or differentiation capacity. One week after the subcutaneous injection of CM-Dil-labeled Muse cells, many cells with orange-red fluorescence were observed at the edges of the skin injuries; those fluorescent spots gradually decreased over time, and only a few Muse cells with fluorescence could be detected by week 5. CM-Dil can be used to label Muse cells without affecting their proliferation, migration or differentiation, and can be used for short-term tracking of Muse cells for the treatment of skin wounds in a rat model.

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.

Characteristics of multilineage-differentiating stress-enduring cell clusters in different culture conditions

OBJECTIVE

To observe the morphological characteristics of clusters of Muse cells from normal human dermal fibroblasts (NHDFs) under different culture conditions.

METHODS

Muse cells were sorted by magnetic activated cell sorting (MACS) from NHDFs, and were evaluated by flow cytometry. Muse cells were cultured in suspension and in adherent conditions to obtain Muse cell clusters (M-clusters), which were further characterized by alkaline phosphatase (AP) staining, immunofluorescence (IF) staining and transmission electron microscopy (TEM). The M-clusters were further cultured on Lando artificial dermal regeneration matrix (LADRM) for analysis by scanning electron microscopy (SEM) and IF staining of frozen sections.

RESULTS

The proportion of SSEA3 and CD105 double-positive cells obtained by MACS was 87.4%. The sorted cells rapidly formed M-clusters after suspension culture, and showed internal characteristics of stem cells under TEM. After adherent culture, M-clusters stained positively for AP, SSEA-3 and OCT-4. Each M-cluster on the surface of the LADRM displayed an outer membrane of amorphous materials under SEM. Frozen sections and fluorescence staining of LADRM loaded with M-clusters showed an uneven fluorescence intensity of SSEA-3 within the clusters.

CONCLUSIONS

Muse cells sorted by MACS from NHDFs could generate M-clusters, which included cells of different stemness and are wrapped in membrane-like structures.

Quantification of the CM-Dil-labeled human umbilical cord mesenchymal stem cells migrated to the dual injured uterus in SD rat

Background

Human umbilical cord mesenchymal stem cell (hUC-MSC) therapy is considered as a promising approach in the treatment of intrauterine adhesions (IUAs). Considerable researches have already detected hUC-MSCs by diverse methods. This paper aims at exploring the quantitative distribution of CM-Dil-labeled hUC-MSCs in different regions of the uterus tissue of the dual injury-induced IUAs in rats and the underlying mechanism of restoration of fertility after implantation of hUC-MSCs in the IUA model.

Methods

In this study, we investigated the quantification of the CM-Dil-labeled hUC-MSCs migrated to the dual injured uterus in Sprague Dawley rats. Additionally, we investigated the differentiation of CM-Dil-labeled hUC-MSCs. The differentiation potential of epithelial cells, vascular endothelial cells, and estrogen receptor (ER) cells were assessed by an immunofluorescence method using CK7, CD31, and ERα. The therapeutic impact of hUC-MSCs in the IUA model was assessed by hematoxylin and eosin, Masson, immunohistochemistry staining, and reproductive function test. Finally, the expression of TGF-β1/Smad3 pathway in uterine tissues was determined by qRT-PCR and Western blotting.

Results

The CM-Dil-labeled cells in the stroma region were significantly higher than those in the superficial myometrium (SM) (71.67 ± 7.98 vs. 60.92 ± 3.96, p = 0.005), in the seroma (71.67 ± 7.98 vs. 23.67 ± 8.08, p = 0.000) and in the epithelium (71.67 ± 7.98 vs. 4.17 ± 1.19, p = 0.000). From the 2nd week of treatment, hUC-MSCs began to differentiate into epithelial cells, vascular endothelial cells, and ER cells. The therapeutic group treated with hUC-MSCs exhibited a significant decrease in fibrosis (TGF-β1/Smad3) as well as a significant increase in vascularization (CD31) compared with the untreated rats.

Conclusion

Our findings suggested that the distribution of the migrated hUC-MSCs in different regions of the uterine tissue was unequal. Most cells were in the stroma and less were in the epithelium of endometrium and gland. Injected hUC-MSCs had a capacity to differentiate into epithelial cells, vascular endothelial cells, and ER cells; increase blood supply; inhibit fibration; and then restore the fertility of the IUA model.

Labeling of human mesenchymal stem cells with different classes of vital stains: robustness and toxicity

Background

Mesenchymal stem cell (MSC) transplantation has been explored as a new clinical approach to repair injured tissues. However, in order to evaluate the therapeutic activity of MSC, cell tracking techniques are required to determine the fate of transplanted cells in both preclinical and clinical studies. In these aspects, different vital stains offer the potential for labeling and monitoring of grafted cells in vivo. It is desirable to have tracking agents which have long-term stability, are not toxic to the cells, and do not affect cell function.

Methods

Here, we selected three different labels: CellTracker™ Green CMFDA, eGFP-mRNA (genetic pre-tag), and Molday ION Rhodamine B™ (nanoparticle-based fluorescent and magnetic label) and performed extensive analysis of their influence on in vitro expansion of human bone marrow-derived mesenchymal stem cells (hBM-MSCs), as well as potential of affecting therapeutic activity and the impact on the durability of staining.

Results

Our study showed that basic hBM-MSC characteristics and functions might be affected by labeling. We observed strong alterations of metabolic activity and morphology after eGFP and CellTracker™ Green CMFDA hBM-MSC staining. Molday ION Rhodamine B™ labeling revealed superior properties relatively to other vital stains. The relative expression level of most of the investigated growth factors remained stable after cell labeling, but we have observed some changes in the case of EGF, GDNF, HGF, and IGF gene expression.

Conclusions

Taken together, we suggest performing similar to ours extensive analysis prior to using any cell label to tag MSC in experiments, as it can thoroughly bias results.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1296-8) contains supplementary material, which is available to authorized users.

Experimental Strategies of Mesenchymal Stem Cell Propagation: Adverse Events and Potential Risk of Functional Changes

Mesenchymal stem cells (MSCs) are attractive candidates for cell-based tissue repair approaches. Hundreds of clinical trials using MSCs have been completed and many others are still being investigated. For most therapeutic applications, MSC propagation in vitro is often required. However, ex vivo culture condition is not fully physiological and may affect biological properties of MSCs including their regenerative potential. Moreover, both cell cryopreservation and labelling procedure prior to infusion may have the negative impact on their expected effect in vivo. The incidence of MSC transformation during in vitro culture should be also taken into consideration before using cells in stem cell therapy. In our review, we focused on different aspects of MSC propagation that might influence their regenerative properties of MSC. We also discussed the influence of different factors that might abolish MSC proliferation and differentiation as well as potential impact of stem cell senescence and aging. Despite of many positive therapeutic effects of MSC therapy, one has to be conscious about potential cell changes that could appear during manufacturing of MSCs.

Conditioned medium from umbilical cord mesenchymal stem cells improves nasal mucosa damage by radiation

OBJECTIVES

To explore therapeutic effects of conditioned medium from human umbilical cord mesenchymal stem cells (hUC-MSCs) on nasal mucosa radiation damage both in vivo and in vitro.

RESULTS

The mucus cilia clearance time (7 and 30 days), degree of mucosal edema (7, 30, 90 and 180 days), cilia coverage (180 days) of concentrated conditioned medium group improved compared with radiotherapy control group. The proliferation and migration abilities of irradiated and non-irradiated nasal epithelial cells significantly increased after culture in bronchial epithelial cell growth medium (BEGM) containing 10% conditioned medium of hUC-MSCs compared to cells cultured in BEGM alone.

CONCLUSIONS

Soluble factors secreted by hUC-MSCs may promote nasal epithelial cell proliferation and migration. Intranasal administration of hUC-MSC conditioned medium effectively repairs nasal mucosa radiation damage.

Internalization of nanopolymeric tracers does not alter characteristics of placental cells

In the cell therapy scenario, efficient tracing of transplanted cells is essential for investigating cell migration and interactions with host tissues. This is fundamental to provide mechanistic insights which altogether allow for the understanding of the translational potential of placental cell therapy in the clinical setting. Mesenchymal stem/stromal cells (MSC) from human placenta are increasingly being investigated for their potential in treating patients with a variety of diseases. In this study, we investigated the feasibility of using poly (methyl methacrylate) nanoparticles (PMMA‐NPs) to trace placental MSC, namely those from the amniotic membrane (hAMSC) and early chorionic villi (hCV‐MSC). We report that PMMP‐NPs are efficiently internalized and retained in both populations, and do not alter cell morphofunctional parameters. We observed that PMMP‐NP incorporation does not alter in vitro immune modulatory capability of placental MSC, a characteristic central to their reparative/therapeutic effects in vitro. We also show that in vitro, PMMP‐NP uptake is not affected by hypoxia. Interestingly, after in vivo brain ischaemia and reperfusion injury achieved by transient middle cerebral artery occlusion (tMCAo) in mice, iv hAMSC treatment resulted in significant improvement in cognitive function compared to PBS‐treated tMCAo mice. Our study provides evidence that tracing placental MSC with PMMP‐NPs does not alter their in vitro and in vivo functions. These observations are grounds for the use of PMMP‐NPs as tools to investigate the therapeutic mechanisms of hAMSC and hCV‐MSC in preclinical models of inflammatory‐driven diseases.

U0126 inhibits pancreatic cancer progression via the KRAS signaling pathway in a zebrafish xenotransplantation model

Pancreatic cancer is one of the most aggressive human cancers, and the pharmaceutical outcomes for its treatment remain disappointing. Proper animal models will provide an efficient platform for investigating novel drugs, and the zebrafish has become one of the most promising and comprehensive model animal in cancer research. In the present study, we used a novel xenograft model in zebrafish by transplanting human pancreatic cancer cells to study the progression and metastasis of pancreatic cancer cells and to assay the pharmacological effects of new drug U0126 in vivo. We first established a primary xenograft model of pancreatic cancer by injecting human pancreatic cancer cells into both live larval and adult zebrafish, and then investigated the behaviors of CM-DiI‑labeled human pancreatic cancer cells. Subsequently, we tested the potential of this model for drug screening by evaluating a known small-molecule inhibitor, U0126, which targets the KRAS signaling pathway. Cells with KRAS mutations exhibited significant proliferative and migratory behaviors and invaded the zebrafish vasculature system. In contrast, the proliferation and migration of Mia PaCa-2 cells in zebrafish larvae were substantially repressed following U0126 treatment. These results suggest that zebrafish xenotransplantation can be used as a simple and efficient tool to screen and identify new anti-pancreatic cancer compounds.

Finding and tracing human MSC in 3D microenvironments with the photoconvertible protein Dendra2

Mesenchymal Stem/Stromal Cells (MSC) are a promising cell type for cell-based therapies - from tissue regeneration to treatment of autoimmune diseases - due to their capacity to migrate to damaged tissues, to differentiate in different lineages and to their immunomodulatory and paracrine properties. Here, a simple and reliable imaging technique was developed to study MSC dynamical behavior in natural and bioengineered 3D matrices. Human MSC were transfected to express a fluorescent photoswitchable protein, Dendra2, which was used to highlight and follow the same group of cells for more than seven days, even if removed from the microscope to the incubator. This strategy provided reliable tracking in 3D microenvironments with different properties, including the hydrogels Matrigel and alginate as well as chitosan porous scaffolds. Comparison of cells mobility within matrices with tuned physicochemical properties revealed that MSC embedded in Matrigel migrated 64% more with 5.2 mg protein/mL than with 9.6 mg/mL and that MSC embedded in RGD-alginate migrated 51% faster with 1% polymer concentration than in 2% RGD-alginate. This platform thus provides a straightforward approach to characterize MSC dynamics in 3D and has applications in the field of stem cell biology and for the development of biomaterials for tissue regeneration.