Mesenchymal stem cells in regenerative rehabilitation

Recent progress in mesenchymal stem cell-based therapy for acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases in critically ill patients. Although pathophysiology of ALI/ARDS has been investigated in many studies, effective therapeutic strategies are still limited. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic intervention for patients with ALI. During the last two decades, researchers have focused on the efficacy and mechanism of MSC application in ALI animal models. MSC derived from variant resources exhibited therapeutic effects in preclinical studies of ALI with different mechanisms. Based on this, clinical studies on MSC treatment in ALI/ARDS has been tried recently, especially in COVID-19 caused lung injury. Emerging clinical trials of MSCs in treating COVID-19-related conditions have been registered in past two years. The advantages and potential of MSCs in the defense against COVID-19-related ALI or ARDS have been confirmed. This review provides a brief overview of recent research progress in MSC-based therapies in preclinical study and clinical trials in ALI treatment, as well as the underlying mechanisms.

Mesenchymal Stem Cell Transplantation: Neuroprotection and Nerve Regeneration After Spinal Cord Injury

Spinal Cord Injury (SCI), with its morbidity characteristics of high disability rate and high mortality rate, is a disease that is highly destructive to both the physiology and psychology of the patient, and for which there is still a lack of effective treatment. Following spinal cord injury, a cascade of secondary injury reactions known as ischemia, peripheral inflammatory cell infiltration, oxidative stress, etc. create a microenvironment that is unfavorable to neural recovery and ultimately results in apoptosis and necrosis of neurons and glial cells. Mesenchymal stem cell (MSC) transplantation has emerged as a more promising therapeutic options in recent years. MSC can promote spinal cord injury repair through a variety of mechanisms, including immunomodulation, neuroprotection, and nerve regeneration, giving patients with spinal cord injury hope. In this paper, it is discussed the neuroprotection and nerve regeneration components of MSCs' therapeutic method for treating spinal cord injuries.

Advances in the application of low-intensity pulsed ultrasound to mesenchymal stem cells

Mesenchymal stem cells (MSCs) are stem cells that exhibit self-renewal capacity and multi-directional differentiation potential. They can be extracted from the bone marrow and umbilical cord, as well as adipose, amnion, and other tissues. They are widely used in tissue engineering and are currently considered an important source of cells in the field of regenerative medicine. Since certain limitations, such as an insufficient cell source, mature differentiation, and low transplantation efficiency, are still associated with MSCs, researchers have currently focused on improving the efficacy of MSCs. Low-intensity pulsed ultrasound (LIPUS) has mechanical, cavitation, and thermal effects that can produce different biological effects on organs, tissues, and cells. It can be used for fracture treatment, cartilage repair, and stem cell applications. An in-depth study of the role and mechanism of action of LIPUS in MSC treatment would promote our understanding of LIPUS and promote research in this field. In this article, we have reviewed the progress in research on the use of LIPUS with various MSCs and comprehensively discussed the progress in the use of LIPUS for promoting the proliferation, differentiation, and migration of MSCs, as well as its future prospects.

MRI detection of the malignant transformation of stem cells through reporter gene expression driven by a tumor-specific promoter

Background

Existing evidence has shown that mesenchymal stem cells (MSCs) can undergo malignant transformation, which is a serious limitation of MSC-based therapies. Therefore, it is necessary to monitor malignant transformation of MSCs via a noninvasive imaging method. Although reporter gene-based magnetic resonance imaging (MRI) has been successfully applied to longitudinally monitor MSCs, this technique cannot distinguish the cells before and after malignant transformation. Herein, we investigated the feasibility of using a tumor-specific promoter to drive reporter gene expression for MRI detection of the malignant transformation of MSCs.

Methods

The reporter gene ferritin heavy chain (FTH1) was modified by adding a promoter from the tumor-specific gene progression elevated gene-3 (PEG3) and transduced into MSCs to obtain MSCs-PEG3-FTH1. Cells were induced to undergo malignant transformation via indirect coculture with C6 glioma cells, and these transformed cells were named MTMSCs-PEG3-FTH1. Western blot analysis of FTH1 expression, Prussian blue staining and transmission electron microscopy (TEM) to detect intracellular iron, and MRI to detect signal changes were performed before and after malignant transformation. Then, the cells before and after malignant transformation were inoculated subcutaneously into nude mice, and MRI was performed to observe the signal changes in the xenografts.

Results

After induction of malignant transformation, MTMSCs demonstrated tumor-like features in morphology, proliferation, migration, and invasion. FTH1 expression was significantly increased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. Prussian blue staining and TEM showed a large amount of iron particles in MTMSCs-PEG3-FTH1 but a minimal amount in MSCs-PEG3-FTH1. MRI demonstrated that the T2 value was significantly decreased in MTMSCs-PEG3-FTH1 compared with MSCs-PEG3-FTH1. In vivo, mass formation was observed in the MTMSCs-PEG3-FTH1 group but not the MSCs-PEG3-FTH1 group. T2-weighted MRI showed a significant signal decrease, which was correlated with iron accumulation in the tissue mass.

Conclusions

We developed a novel MRI model based on FTH1 reporter gene expression driven by the tumor-specific PEG3 promoter. This approach could be applied to sensitively detect the occurrence of MSC malignant transformation.

Measurement of Bone Mineral Density in Children with Cerebral Palsy from an Ethical Issue to a Diagnostic Necessity

Introduction

Due to concerns about cumulative radiation exposure in the pediatric population, it is not standard practice to perform dual-energy X-ray absorptiometry (DXA) analysis in the diagnostic process of musculoskeletal disorders, such as cerebral palsy (CP). This study aimed to evaluate the bone mineral density (BMD) in children with CP and the ethical justification of applying DXA analysis in these children. Material and Methods. In this monocentric retrospective analysis, data were collected from children and adolescents with CP who were treated for a primary illness for three years. A clinical examination, which included a DXA analysis, recommended by the multidisciplinary team, was performed. After applying inclusion and exclusion criteria, 60 scans remained for statistical analysis. BMD and Z-scores for the lumbar spine (LS), and hip right and left femoral neck (RFN and LFN, respectively), and total hip (TH) were recorded.

Results

The average age of children with CP when DXA analysis was first performed was about 7 years. The BMD (mean ± SD) at LS (LS-BMD) of all patients was 0.612 ± 0.12, at RFN 0.555 ± 0.11, at LFN 0.572 ± 0.1, and at TH (TH-BMD) 0.581 ± 0.13. The values of the Z-score (mean ± SD) at LS of all patients were −2.5 ± 0.22, at RFN −2.2 ± 0.21, at LFN -2.25 (SD = 0.2), and at TH -2.3 (SD = 0.23). There was no statistical significance between age and gender; however, BMI, walking ability, fracture history, and pattern of CP had a significant impact on BMD and Z-score values of these children.

Conclusion

The results of our study clearly indicate that children with CP have a higher risk of low BMD, osteoporosis, and bone fractures, which makes it ethically justifiable to perform the DXA analysis in these children.

Hopes and Limits of Adipose-Derived Stem Cells (ADSCs) and Mesenchymal Stem Cells (MSCs) in Wound Healing

Adipose tissue derived stem cells (ADSCs) are mesenchymal stem cells identified within subcutaneous tissue at the base of the hair follicle (dermal papilla cells), in the dermal sheets (dermal sheet cells), in interfollicular dermis, and in the hypodermis tissue. These cells are expected to play a major role in regulating skin regeneration and aging-associated morphologic disgraces and structural deficits. ADSCs are known to proliferate and differentiate into skin cells to repair damaged or dead cells, but also act by an autocrine and paracrine pathway to activate cell regeneration and the healing process. During wound healing, ADSCs have a great ability in migration to be recruited rapidly into wounded sites added to their differentiation towards dermal fibroblasts (DF), endothelial cells, and keratinocytes. Additionally, ADSCs and DFs are the major sources of the extracellular matrix (ECM) proteins involved in maintaining skin structure and function. Their interactions with skin cells are involved in regulating skin homeostasis and during healing. The evidence suggests that their secretomes ensure: (i) The change in macrophages inflammatory phenotype implicated in the inflammatory phase, (ii) the formation of new blood vessels, thus promoting angiogenesis by increasing endothelial cell differentiation and cell migration, and (iii) the formation of granulation tissues, skin cells, and ECM production, whereby proliferation and remodeling phases occur. These characteristics would be beneficial to therapeutic strategies in wound healing and skin aging and have driven more insights in many clinical investigations. Additionally, it was recently presented as the tool key in the new free-cell therapy in regenerative medicine. Nevertheless, ADSCs fulfill the general accepted criteria for cell-based therapies, but still need further investigations into their efficiency, taking into consideration the host-environment and patient-associated factors.

Adipose Tissue-Derived Mesenchymal Stem Cells Protect Against Amiodarone-Induced Lung Injury in Rats

Pulmonary fibrosis (PF) is a progressive and irreversible lung disease, characterized by poor prognosis with limited treatment options. Mesenchymal stem cells (MSCs) are multi-potent cells having the ability to self-renew and differentiate into multiple tissues, thus considered a novel treatment option. The present study aimed to investigate the possible antifibrotic effect of undifferentiated adipose tissue-derived mesenchymal stem cell (AD-MSC) therapy on PF experimentally induced in rats using amiodarone (AMD). AMD (30 mg/kg) was given orally, once daily for 12 consecutive weeks to induce lung fibrosis. Following the confirmation of lung damage with histopathological examination, AD-MSCs (2 × 10⁶ and 4 × 10⁶ undifferentiated MSCs) were injected once intravenously, followed by 2 months for treatment. AMD induced focal fibroblastic cells proliferation in the peribronchiolar tissue, as well as in between the collapsed emphysematous alveoli. Also, AMD significantly increased serum and lung homogenate fibroblast growth factor-7 (FGF7), Clara cell protein-16 (CC16), and cytokeratin -19 (CK19) levels, as well as the expression of both iNOS and NFкB in the lung alveoli. Moreover, AMD caused excessive collagen deposition and increased alpha smooth muscle actin (α-SMA) expression. All findings significantly regressed on stem cell therapy in both doses, with superior effect of the high dose, providing evidence that adipose tissue-derived MSCs could be a promising approach for the treatment of PF. Graphical Abstract.

Adipose Tissue Graft Improves Early but not Late Stages of Nerve Regeneration

AIM

The aim of the study was to assess the effect of autologous fat graft on nerve regeneration by means of immunohistochemistry.

MATERIALS AND METHODS

The rat sciatic nerve was used; complete transection followed by primary neurorrhaphy was performed on both hind legs, on the left side a processed fat graft was applied, surrounding the nerve. Nerve biopsies were collected and immunohistochemical procedures were performed for glial fibrillary acidic protein (GFAP) and for neurofilament-associated protein(NFAP).

RESULTS

At 4 weeks, GFAP-positive cells were observed in the connective tissue formed between the two nerve endings on the left side only. At 10 weeks, GFAP-positive structures were present and exhibited a tendency to become linear on both sides, with an increased density on the left. NFAP-positive expression was present in the left treated limb with a disorganized pattern.

CONCLUSION

Adipose tissue led to the stimulation of GFAP-positive Schwann cells, which could have a positive impact on nerve regeneration in the clinical setting.

Accumulation of spontaneous γH2AX foci in long-term cultured mesenchymal stromal cells

Expansion of mesenchymal stromal/stem cells (MSCs) used in clinical practices may be associated with accumulation of genetic instability. Understanding temporal and mechanistic aspects of this process is important for improving stem cell therapy protocols. We used γH2AX foci as a marker of a genetic instability event and quantified it in MSCs that undergone various numbers of passage (3-22). We found that γH2AX foci numbers increased in cells of late passages, with a sharp increase at passage 16-18. By measuring in parallel foci of ATM phosphorylated at Ser-1981 and their co-localization with γH2AX foci, along with differentiating cells into proliferating and resting by using a Ki67 marker, we conclude that the sharp increase in γH2AX foci numbers was ATM-independent and happened predominantly in proliferating cells. At the same time, gradual and moderate increase in γH2AX foci with passage number seen in both resting and proliferating cells may represent a slow, DNA double-strand break related component of the accumulation of genetic instability in MSCs. Our results provide important information on selecting appropriate passage numbers exceeding which would be associated with substantial risks to a patient-recipient, both with respect to therapeutic efficiency and side-effects related to potential neoplastic transformations due to genetic instability acquired by MSCs during expansion.

Amniotic Mesenchymal Stromal Cells Exhibit Preferential Osteogenic and Chondrogenic Differentiation and Enhanced Matrix Production Compared With Adipose Mesenchymal Stromal Cells

BACKGROUND

Therapeutic efficacy of various mesenchymal stromal cell (MSC) types for orthopaedic applications is currently being investigated. While the concept of MSC therapy is well grounded in the basic science of healing and regeneration, little is known about individual MSC populations in terms of their propensity to promote the repair and/or regeneration of specific musculoskeletal tissues. Two promising MSC sources, adipose and amnion, have each demonstrated differentiation and extracellular matrix (ECM) production in the setting of musculoskeletal tissue regeneration. However, no study to date has directly compared the differentiation potential of these 2 MSC populations.

PURPOSE

To compare the ability of human adipose- and amnion-derived MSCs to undergo osteogenic and chondrogenic differentiation.

STUDY DESIGN

Controlled laboratory study.

METHODS

MSC populations from the human term amnion were quantified and characterized via cell counting, histologic assessment, and flow cytometry. Differentiation of these cells in comparison to commercially purchased human adipose-derived mesenchymal stromal cells (hADSCs) in the presence and absence of differentiation media was evaluated via reverse transcription polymerase chain reaction (PCR) for bone and cartilage gene transcript markers and histology/immunohistochemistry to examine ECM production. Analysis of variance and paired t tests were performed to compare results across all cell groups investigated.

RESULTS

The authors confirmed that the human term amnion contains 2 primary cell types demonstrating MSC characteristics-(1) human amniotic epithelial cells (hAECs) and (2) human amniotic mesenchymal stromal cells (hAMSCs)-and each exhibited more than 90% staining for MSC surface markers (CD90, CD105, CD73). Average viable hAEC and hAMSC yields at harvest were 2.3 × 10⁶ ± 3.7 × 10⁵ and 1.6 × 10⁶ ± 4.7 × 10⁵ per milliliter of amnion, respectively. As well, hAECs and hAMSCs demonstrated significantly greater osteocalcin ( P = .025), aggrecan ( P < .0001), and collagen type 2 ( P = .044) gene expression compared with hADSCs, respectively, after culture in differentiation medium. Moreover, both hAECs and hAMSCs produced significantly greater quantities of mineralized ( P < .0001) and cartilaginous ( P = .0004) matrix at earlier time points compared with hADSCs when cultured under identical osteogenic and chondrogenic differentiation conditions, respectively.

CONCLUSION

Amnion-derived MSCs demonstrate a greater differentiation potential toward bone and cartilage compared with hADSCs.

CLINICAL RELEVANCE

Amniotic MSCs may be the source of choice in the regenerative treatment of bone or osteochondral musculoskeletal disease. They show significantly higher yields and better differentiation toward these tissues than MSCs derived from adipose.

Cell therapy for lung disease

Besides cancer and cardiovascular diseases, lung disorders are a leading cause of morbidity and death worldwide. For many disease conditions no effective and curative treatment options are available. Cell therapies offer a novel therapeutic approach due to their inherent anti-inflammatory and anti-fibrotic properties. Mesenchymal stem/stromal cells (MSC) are the most studied cell product. Numerous preclinical studies demonstrate an improvement of disease-associated parameters after MSC administration in several lung disorders, including chronic obstructive pulmonary disease, acute respiratory distress syndrome and idiopathic pulmonary fibrosis. Furthermore, results from clinical studies using MSCs for the treatment of various lung diseases indicate that MSC treatment in these patients is safe. In this review we summarise the results of preclinical and clinical studies that indicate that MSCs are a promising therapeutic approach for the treatment of lung diseases. Nevertheless, further investigations are required.