Ultrasound Irradiation Combined with Hepatocyte Growth Factor Accelerate the Hepatic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Recent advancement of sonogenetics: A promising noninvasive cellular manipulation by ultrasound

Recent advancements in biomedical research have underscored the importance of noninvasive cellular manipulation techniques. Sonogenetics, a method that uses genetic engineering to produce ultrasound-sensitive proteins in target cells, is gaining prominence along with optogenetics, electrogenetics, and magnetogenetics. Upon stimulation with ultrasound, these proteins trigger a cascade of cellular activities and functions. Unlike traditional ultrasound modalities, sonogenetics offers enhanced spatial selectivity, improving precision and safety in disease treatment. This technology broadens the scope of non-surgical interventions across a wide range of clinical research and therapeutic applications, including neuromodulation, oncologic treatments, stem cell therapy, and beyond. Although current literature predominantly emphasizes ultrasonic neuromodulation, this review offers a comprehensive exploration of sonogenetics. We discuss ultrasound properties, the specific ultrasound-sensitive proteins employed in sonogenetics, and the technique's potential in managing conditions such as neurological disorders, cancer, and ophthalmic diseases, and in stem cell therapies. Our objective is to stimulate fresh perspectives for further research in this promising field.

Latest progress in low-intensity pulsed ultrasound for studying exosomes derived from stem/progenitor cells

Stem cells have self-renewal, replication, and multidirectional differentiation potential, while progenitor cells are undifferentiated, pluripotent or specialized stem cells. Stem/progenitor cells secrete various factors, such as cytokines, exosomes, non-coding RNAs, and proteins, and have a wide range of applications in regenerative medicine. However, therapies based on stem cells and their secreted exosomes present limitations, such as insufficient source materials, mature differentiation, and low transplantation success rates, and methods addressing these problems are urgently required. Ultrasound is gaining increasing attention as an emerging technology. Low-intensity pulsed ultrasound (LIPUS) has mechanical, thermal, and cavitation effects and produces vibrational stimuli that can lead to a series of biochemical changes in organs, tissues, and cells, such as the release of extracellular bodies, cytokines, and other signals. These changes can alter the cellular microenvironment and affect biological behaviors, such as cell differentiation and proliferation. Here, we discuss the effects of LIPUS on the biological functions of stem/progenitor cells, exosomes, and non-coding RNAs, alterations involved in related pathways, various emerging applications, and future perspectives. We review the roles and mechanisms of LIPUS in stem/progenitor cells and exosomes with the aim of providing a deeper understanding of LIPUS and promoting research and development in this field.

Sonomechanobiology: Vibrational stimulation of cells and its therapeutic implications

All cells possess an innate ability to respond to a range of mechanical stimuli through their complex internal machinery. This comprises various mechanosensory elements that detect these mechanical cues and diverse cytoskeletal structures that transmit the force to different parts of the cell, where they are transcribed into complex transcriptomic and signaling events that determine their response and fate. In contrast to static (or steady) mechanostimuli primarily involving constant-force loading such as compression, tension, and shear (or forces applied at very low oscillatory frequencies (≤ 1 Hz) that essentially render their effects quasi-static), dynamic mechanostimuli comprising more complex vibrational forms (e.g., time-dependent, i.e., periodic, forcing) at higher frequencies are less well understood in comparison. We review the mechanotransductive processes associated with such acoustic forcing, typically at ultrasonic frequencies (> 20 kHz), and discuss the various applications that arise from the cellular responses that are generated, particularly for regenerative therapeutics, such as exosome biogenesis, stem cell differentiation, and endothelial barrier modulation. Finally, we offer perspectives on the possible existence of a universal mechanism that is common across all forms of acoustically driven mechanostimuli that underscores the central role of the cell membrane as the key effector, and calcium as the dominant second messenger, in the mechanotransduction process.

HPF Modulates the Differentiation of BMSCs into HLCs and Promotes the Recovery of Acute Liver Injury in Mice

Bone marrow-derived mesenchymal stem cells (BMSCs) can differentiate into hepatocyte-like cells (HLCs) to alleviate acute liver injury (ALI). Herpetfluorenone (HPF), as an active ingredient in the dried, mature seeds Herpetospermum caudigerum Wall, used in Tibetan medicine, has been proven to effectively alleviate ALI. Therefore, the purpose of this study was to determine whether HPF can promote the differentiation of BMSCs into HLCs and promote ALI recovery. Mouse BMSCs were isolated, and the BMSCs’ differentiation into HLCs was induced by HPF and hepatocyte growth factor (HGF). Under the induction of HPF and HGF, the expression of hepatocellular specific markers and the accumulation of glycogen and lipids in the BMSCs increased, indicating that BMSCs successfully differentiated into HLCs. Then, the ALI mouse model was established, using carbon tetrachloride, followed by an intravenous injection of BMSCs. Then, only HPF was injected intraperitoneally, in order to verify the effect of HPF in vivo. In vivo imaging was used to detect the homing ability of HPF–BMSCs, and it was detected that HPF–BMSCs significantly increased the levels of serum AST, ALT and ALP in the liver of ALI mice, and alleviated liver cell necrosis, oxidative stress and liver pathology. In conclusion, HPF can promote the differentiation of BMSCs into HLCs and promote the recovery of ALI in mice.

Application of low-intensity pulsed ultrasound on tissue resident stem cells: Potential for ophthalmic diseases

INTRODUCTION

Tissue-resident stem cells (TRSCs) have the ability to self-renew and differentiate throughout an individual's lifespan, and they utilize both mechanisms to maintain homeostasis and regenerate damaged tissues. Several studies suggest that these stem cells can serve as a potential source for cell-replacement-based therapy by promoting differentiation or expansion. In recent years, low-intensity pulsed ultrasound (LIPUS) has been demonstrated to effectively stimulate stem cell proliferation and differentiation, promote tissue regeneration, and inhibit inflammatory responses.

AIMS

To present a comprehensive overview of current application and mechanism of LIPUS on tissue resident stem cells.

METHODS

We searched PubMed, Web of Science for articles on the effects of LIPUS on tissue resident stem cells and its application.

RESULTS

The LIPUS could modulate cellular activities such as cell viability, proliferation and differentiation of tissue resident stem cells and related cells through various cellular signaling pathways. Currently, LIPUS, as the main therapeutic ultrasound, is being widely used in the treatment of preclinical and clinical diseases.

CONCLUSION

The stem cell research is the hot topic in the biological science, while in recent years, increasing evidence has shown that TRSCs are good targets for LIPUS-regulated regenerative medicine. LIPUS may be a novel and valuable therapeutic approach for the treatment of ophthalmic diseases. How to further improve its efficiency and accuracy, as well as the biological mechanism therein, will be the focus of future research.

Production and Biological Effects of Extracellular Vesicles from Adipose-Derived Stem Cells Were Markedly Increased by Low-Intensity Ultrasound Stimulation for Promoting Diabetic Wound Healing

Diabetic wound treatment has posed a significant challenge in clinical practice. As a kind of cell-derived nanoparticles, extracellular vesicles produced by adipose-derived stem cells (ADSC-EVs) have been reported to be potential agents for diabetic wound treatment. However, ADSC-EV yield is insufficient to meet the demands of clinical therapy. In this study, a novel method involving the use of low-intensity ultrasound stimulation on ADSCs is developed to promote EV secretion for clinical use. A proper low-intensity ultrasound stimulation parameter which significantly increases ADSC-EV quantity has been found. In addition, EVs secreted by ADSCs following low-intensity ultrasound stimulation (US-EVs) are enriched in wound healing-related miRNAs. Moreover, US-EVs promote the biological functions of fibroblasts, keratinocytes, and endothelial cells in vitro, and promote diabetic wound healing in db/db mice in vivo through re-epithelialization, collagen production, cell proliferation, keratinocyte differentiation and migration, and angiogenesis. This study proposes low-intensity ultrasound stimulation as a new method for promoting significant EV secretion by ADSCs and for improving the diabetic wound-healing potential of EVs, which will meet the clinical needs for these nanoparticles. The production of extracellular vesicles of adipose-derived stem cells is obviously promoted by a low-intensity ultrasound stimulation method, and the biological effects of promoting diabetic wound healing were markedly increased in vitro and in vivo.

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.

Low-Intensity Pulsed Ultrasound Promotes Osteogenic Potential of iPSC-Derived MSCs but Fails to Simplify the iPSC-EB-MSC Differentiation Process

Induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells (iMSCs) are a promising cell source for bone tissue engineering. However, iMSCs have less osteogenic potential than BMSCs, and the classical iPSC-EB-iMSC process to derive iMSCs from iPSCs is too laborious as it involves multiple in vitro steps. Low-intensity pulsed ultrasound (LIPUS) is a safe therapeutic modality used to promote osteogenic differentiation of stem cells. Whether LIPUS can facilitate osteogenic differentiation of iMSCs and simplify the iPSC-EB-iMSC process is unknown. We stimulated iMSCs with LIPUS at different output intensities (20, 40, and 60 mW/cm²) and duty cycles (20, 50, and 80%). Results of ALP activity assay, osteogenic gene expression, and mineralization quantification demonstrated that LIPUS was able to promote osteogenic differentiation of iMSCs, and it worked best at the intensity of 40 mW/cm² and the duty cycle of 50% (LIPUS40/50). The Wnt/β-catenin signaling pathway was involved in LIPUS40/50-mediated osteogenesis. When cranial bone defects were implanted with iMSCs, LIPUS40/50 stimulation resulted in a significant higher new bone filling rate (72.63 ± 17.04)% than the non-stimulated ones (34.85 ± 4.53)%. Daily exposure to LIPUS40/50 may accelerate embryoid body (EB)-MSC transition, but it failed to drive iPSCs or EB cells to an osteogenic lineage directly. This study is the first to demonstrate the pro-osteogenic effect of LIPUS on iMSCs. Although LIPUS40/50 failed to simplify the classical iPSC-EB-MSC differentiation process, our preliminary results suggest that LIPUS with a more suitable parameter set may achieve the goal. LIPUS is a promising method to establish an efficient model for iPSC application.

Long noncoding RNA SNHG1 silencing accelerates hepatocyte-like cell differentiation of bone marrow-derived mesenchymal stem cells to alleviate cirrhosis via the microRNA-15a/SMURF1/UVRAG axis

Bone marrow-derived mesenchymal stem cells (BMSCs) can differentiate into hepatocyte-like cells (HLCs) to attenuate cirrhosis. Long noncoding RNA (lncRNA) SNHG1 has been demonstrated to orchestrate BMSC differentiation, whereas its role in cirrhosis remains elusive. Therefore, this study was performed to figure out whether lncRNA SNHG1 was involved in cirrhosis by affecting HLC differentiation of BMSCs. Mouse BMSCs were isolated, and the BMSC differentiation into HLCs was induced by hepatocyte growth factor (HGF). A cirrhotic mouse model was established using carbon tetrachloride and phenobarbital, followed by intravenous injection of BMSCs with manipulated expression of lncRNA SNHG1, microRNA (miR)-15a, and SMURF1. Subsequent to HGF induction, expression of hepatocyte-related genes, albumin secretion, and glycogen accumulation was increased in BMSCs, suggesting the differentiation of BMSCs into HLCs. Mechanistically, lncRNA SNHG1 bound to miR-15a that targeted SMURF1, and SMURF1 diminished ATG5 and Wnt5a expression by enhancing the ubiquitination of UVRAG. LncRNA SNHG1 or SMURF1 silencing or miR-15a overexpression promoted differentiation of BMSCs into HLCs and repressed cirrhosis of mice by upregulating ATG5 and Wnt5a via UVRAG. Conclusively, lncRNA SNHG1 silencing might facilitate HLC differentiation from mouse BMSCs and alleviate cirrhosis via the miR-15a/SMURF1/UVRAG/ATG5/Wnt5a axis.

Regulation of stem cell fate using nanostructure-mediated physical signals

One of the major issues in tissue engineering is regulation of stem cell differentiation toward specific lineages. Unlike biological and chemical signals, physical signals with adjustable properties can be applied to stem cells in a timely and localized manner, thus making them a hot topic for research in the fields of biomaterials, tissue engineering, and cell biology. According to the signals sensed by cells, physical signals used for regulating stem cell fate can be classified into six categories: mechanical, light, thermal, electrical, acoustic, and magnetic. In most cases, external macroscopic physical fields cannot be used to modulate stem cell fate, as only the localized physical signals accepted by the surface receptors can regulate stem cell differentiation via nanoscale fibrin polysaccharide fibers. However, surface receptors related to certain kinds of physical signals are still unknown. Recently, significant progress has been made in the development of functional materials for energy conversion. Consequently, localized physical fields can be produced by absorbing energy from an external physical field and subsequently releasing another type of localized energy through functional nanostructures. Based on the above concepts, we propose a methodology that can be utilized for stem cell engineering and for the regulation of stem cell fate via nanostructure-mediated physical signals. In this review, the combined effect of various approaches and mechanisms of physical signals provides a perspective on stem cell fate promotion by nanostructure-mediated physical signals. We expect that this review will aid the development of remote-controlled and wireless platforms to physically guide stem cell differentiation both in vitro and in vivo, using optimized stimulation parameters and mechanistic investigations while driving the progress of research in the fields of materials science, cell biology, and clinical research.

Ultrasound-Enabled Therapeutic Delivery and Regenerative Medicine: Physical and Biological Perspectives

The role of ultrasound in medicine and biological sciences is expanding rapidly beyond its use in conventional diagnostic imaging. Numerous studies have reported the effects of ultrasound on cellular and tissue physiology. Advances in instrumentation and electronics have enabled successful in vivo applications of therapeutic ultrasound. Despite path breaking advances in understanding the biophysical and biological mechanisms at both microscopic and macroscopic scales, there remain substantial gaps. With the progression of research in this area, it is important to take stock of the current understanding of the field and to highlight important areas for future work. We present herein key developments in the biological applications of ultrasound especially in the context of nanoparticle delivery, drug delivery, and regenerative medicine. We conclude with a brief perspective on the current promise, limitations, and future directions for interfacing ultrasound technology with biological systems, which could provide guidance for future investigations in this interdisciplinary area.

Progress of Interference of Traditional Chinese Medicine on Cirrhosis Treated with Bone Marrow Mesenchymal Stem Cells

Transplantation of bone marrow mesenchymal stem cells has attracted more and more attention as a regenerative therapy for the treatment of liver diseases. A large number of studies have shown that this kind of cells can inhibit the activation of hepatic stellate cells and regulate tissue homeostasis and immune system via a variety of ways. Meanwhile, bone marrow mesenchymal stem cells can inhibit apoptosis of hepatocyte, improve liver function, and reduce inflammation through multiple pathways. These cells have a broad prospect in the treatment of liver cirrhosis. At present, there are many studies on the specific mechanism of bone marrow mesenchymal stem cells transplantation in the treatment of liver cirrhosis. This paper reviews the pathogenesis of liver cirrhosis and the mechanism of bone marrow mesenchymal stem cells transplantation in the treatment of liver cirrhosis, discusses the effectiveness of traditional Chinese medicine method in enhancing the efficacy of bone marrow mesenchymal stem cells transplantation, and looks forward to its application prospect in the future.

Ultrasound Therapy: Experiences and Perspectives for Regenerative Medicine

Ultrasound has emerged as a novel tool for clinical applications, particularly in the context of regenerative medicine. Due to its unique physico-mechanical properties, low-intensity ultrasound (LIUS) has been approved for accelerated fracture healing and for the treatment of established non-union, but its utility has extended beyond tissue engineering to other fields, including cell regeneration. Cells and tissues respond to acoustic ultrasound by switching on genetic repair circuits, triggering a cascade of molecular signals that promote cell proliferation, adhesion, migration, differentiation, and extracellular matrix production. LIUS also induces angiogenesis and tissue regeneration and has anti-inflammatory and anti-degenerative effects. Accordingly, the potential application of ultrasound for tissue repair/regeneration has been tested in several studies as a stand-alone treatment and, more recently, as an adjunct to cell-based therapies. For example, ultrasound has been proposed to improve stem cell homing to target tissues due to its ability to create a transitional and local gradient of cytokines and chemokines. In this review, we provide an overview of the many applications of ultrasound in clinical medicine, with a focus on its value as an adjunct to cell-based interventions. Finally, we discuss the various preclinical and clinical studies that have investigated the potential of ultrasound for regenerative medicine.

The role of ultrasound in enhancing mesenchymal stromal cell-based therapies

Mesenchymal stromal cells (MSCs) have been a popular platform for cell‐based therapy in regenerative medicine due to their propensity to home to damaged tissue and act as a repository of regenerative molecules that can promote tissue repair and exert immunomodulatory effects. Accordingly, a great deal of research has gone into optimizing MSC homing and increasing their secretion of therapeutic molecules. A variety of methods have been used to these ends, but one emerging technique gaining significant interest is the use of ultrasound. Sound waves exert mechanical pressure on cells, activating mechano‐transduction pathways and altering gene expression. Ultrasound has been applied both to cultured MSCs to modulate self‐renewal and differentiation, and to tissues‐of‐interest to make them a more attractive target for MSC homing. Here, we review the various applications of ultrasound to MSC‐based therapies, including low‐intensity pulsed ultrasound, pulsed focused ultrasound, and extracorporeal shockwave therapy, as well as the use of adjunctive therapies such as microbubbles. At a molecular level, it seems that ultrasound transiently generates a local gradient of cytokines, growth factors, and adhesion molecules that facilitate MSC homing. However, the molecular mechanisms underlying these methods are far from fully elucidated and may differ depending on the ultrasound parameters. We thus put forth minimal criteria for ultrasound parameter reporting, in order to ensure reproducibility of studies in the field. A deeper understanding of these mechanisms will enhance our ability to optimize this promising therapy to assist MSC‐based approaches in regenerative medicine.

Long-term Production of Glycogen and Hepatic-Derived, Cell-Invasion-Promoting Chemokines by Ultrasound-Driven Hepatic-Differentiated Human Bone Marrow Mesenchymal Stem Cells

The current treatment for liver failure is restricted to surgical liver transplantation, which is technically complicated, limited by the shortage of available organs and presents major risks to the patient. Bone marrow mesenchymal stem cells (BMSCs) represent promising sources of hepatocyte-like cells for cell transplantation treatment. However, a safe and efficient induction method for their differentiation remains to be defined. Here we further optimized an effective technique by combining high-dose treatment with hepatocyte growth factor (HGF) and ultrasound stimulation. The optimized ultrasound parameter (1.0 W/cm² intensity, 1 MHz frequency, 20% duty cycle, 100 Hz pulse repetition frequency, 60-s irradiation duration, triple times in three days) combined with different HGF doses (10, 20 and 50 ng/ml) was used to treat BMSCs. The results showed that the specific hepatic markers, including α-fetoprotein (αFP/AFP), cytokeratin 18 (CK18), albumin (ALB) and glycogen, were increased in a dose-dependent manner. Their concentration was then further increased when ultrasound irradiation was administered (P < 0.05), as indicated by PCR, Western blot and immunofluorescence staining as well as a glycogen synthesis test. Furthermore, analysis of the hepatocyte-derived chemokines showed elevated stromal cell-derived factor 1alpha (SDF-1α) and C-X-C chemokine receptor type 4 (CXCR4) after HGF treatment. Again, concentrations of those chemokines were further increased by ultrasound radiation (P < 0.05). The observed increased effect was sustained for 21 days. To summarize, we further defined the optimal combination of HGF and ultrasound treatment to increase the differentiation and chemotaxis of BMSCs in a safe, sustained and efficient manner. These findings provide a new perspective for stem cell orientation in the field of tissue engineering.

Impact of Ultrasound Therapy on Stem Cell Differentiation - A Systematic Review

OBJECTIVE

This is a systematic review of the effects of low-intensity pulsed ultrasound (LIPUS) on stem cell differentiation.

BACKGROUND DATA

Recent studies have investigated several types of stem cells from different sources in the body. These stem cells should strictly be certified and promoted for cell therapies before being used in medical applications. LIPUS has been used extensively in treatment centers and in research to promote stem cell differentiation, function, and proliferation.

MATERIALS AND METHODS

The databases of PubMed, Google Scholar, and Scopus were searched for abstracts and full-text scientific papers published from 1989-2019 that reported the application of LIPUS on stem cell differentiation. Related English language articles were found using the following defined keywords: low-intensity pulsed ultrasound, stem cell, differentiation. Criteria for inclusion in the review were: LIPUS with frequencies of 1-3 MHz and pulsed ultrasound intensity of <500 mW/cm2. Duration, exposure time, and cell sources were taken into consideration.

RESULTS

Fifty-two articles were selected based on the inclusion criteria. Most articles demonstrated that the application of LIPUS had positive effects on stem cell differentiation. However, some authors recommended that LIPUS combined with other physical therapy aides was more effective in stem cell differentiation.

CONCLUSION

LIPUS significantly increases the level of stem cell differentiation in cells derived mainly from bone marrow mesenchymal stem cells. There is a need for further studies to analyze the effect of LIPUS on cells derived from other sources, particularly adipose tissue-derived mesenchymal stem cells, for treating hard diseases, such as osteoporosis and diabetic foot ulcer. Due to a lack of reporting on standard LIPUS parameters in the field, more experiments comparing the protocols for standardization of LIPUS parameters are needed to establish the best protocol, which would allow for the best results.

Modulation of the Notch System in Response to Wnt Inhibition Induces Restoration of the Rat Luteal Function

The aim of this study was to investigate whether the Notch pathway is modulated in response to the downregulation of the Wnt/Β-catenin system in corpora lutea (CLs) from superovulated rats. To this end, we analyzed the effect of in vitro CL Wnt/Β-catenin inhibition on the expression of Notch members and on luteal function. Mechanically isolated rat CLs were cultured with ICG-001, a Wnt/B-catenin inhibitor. In this system, Wnt/B-catenin inhibition reduced progesterone production and decreased StAR protein levels. Besides, Wnt/B-catenin inhibition stimulated the Notch system, evidenced by an increase in Hes1 expression, and promoted the expression of selected Notch family members. At long incubation times, StAR levels and progesterone concentration reached the control values, effects probably mediated by the Notch pathway. These results provide the first evidence of a compensatory mechanism between Wnt/B-catenin signaling and the Notch system, which contributes to the homeostasis of luteal cells.

Inhibition of MSTN signal pathway may participate in LIPUS preventing bone loss in ovariectomized rats

INTRODUCTION

Menopause can lead to osteoporosis, which is characterized by destruction of bone microstructure, poor mechanical properties, and prone to fracture. LIPUS can effectively promote bone formation and fracture healing. MSTN is a transforming growth factor-β family member that acts as a negative regulator of skeletal muscle growth. A MSTN deficiency also has a positive effect on bone formation. However, whether LIPUS could inhibit bone loss and promote healing of bone injury of menopause through the inhibition of the MSTN signaling pathway has not been previously investigated. We herein investigated the effects of LIPUS on bone architecture, mechanical properties, the healing of bone defects, and its potential molecular mechanisms in ovariectomized rats.

MATERIALS AND METHODS

The rats were randomly divided into three groups: sham ovariectomized group (Sham), ovariectomized model group (OVX), ovariectomized model with LIPUS therapy group (OVX + LIPUS). The OVX + LIPUS rats were treated with LIPUS (1.5 MHz, 30 mW/cm²) on the femur for 20 min/day that lasted for 19 days.

RESULTS

LIPUS effectively improved the bone microstructure, increased mechanical properties and promoted the healing of bone defects in ovariectomized rats. Moreover, LIPUS effectively decreased the MSTN content in serum and quadriceps muscle in ovariectomized rats, and inhibited the expression of MSTN downstream signaling molecules and activated the Wnt signaling pathway in the femur.

CONCLUSIONS

The present study shows that LIPUS improved osteoporosis and promoted bone defect healing in the ovariectomized rats may through the inhibition of the MSTN signal pathway.

Regulation and Directing Stem Cell Fate by Tissue Engineering Functional Microenvironments: Scaffold Physical and Chemical Cues

It is well known that stem cells reside within tissue engineering functional microenvironments that physically localize them and direct their stem cell fate. Recent efforts in the development of more complex and engineered scaffold technologies, together with new understanding of stem cell behavior in vitro, have provided a new impetus to study regulation and directing stem cell fate. A variety of tissue engineering technologies have been developed to regulate the fate of stem cells. Traditional methods to change the fate of stem cells are adding growth factors or some signaling pathways. In recent years, many studies have revealed that the geometrical microenvironment played an essential role in regulating the fate of stem cells, and the physical factors of scaffolds including mechanical properties, pore sizes, porosity, surface stiffness, three-dimensional structures, and mechanical stimulation may affect the fate of stem cells. Chemical factors such as cell-adhesive ligands and exogenous growth factors would also regulate the fate of stem cells. Understanding how these physical and chemical cues affect the fate of stem cells is essential for building more complex and controlled scaffolds for directing stem cell fate.

Inducing differentiation of human urine-derived stem cells into hepatocyte-like cells by coculturing with human hepatocyte L02 cells

OBJECTIVES

To investigate the possibility of inducing differentiation of human urine-derived stem cells (hUSCs) into hepatocyte-like cells by coculturing with human hepatocyte L02 cells in vitro.

METHODS

HUSCs were isolated from fresh urine samples collected from healthy adult volunteers by centrifugation. Cells were observed under an inverted phase contrast microscope, and proliferative activity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Stem cell surface markers were detected by flow cytometry. HUSCs were induced to differentiate into hepatocyte-like cells by coculturing with human hepatocyte L02 cells, which were confirmed by cellular morphology, messenger RNA expression of albumin (ALB), α-fetoprotein (AFP) and hepatocyte cytochrome P450 (CYP450) analyzed with quantitative reverse transcription polymerase chain reaction and the expression of glycogen detected by glycogen staining kits at 5, 10, and 15 days after coculturing.

RESULTS

HUSCs from urine were successfully isolated and cultured in vitro. At passages 3, the growth curve of hUSCs was S-shaped with good proliferation activity. Mesenchymal stem cell surface markers CD44 and CD90 were detected positive by flow cytometry. CD31 for endothelial cells and CD34 for hematopoietic stem cell markers were not detected. HUSCs gained the cellular morphology and function of hepatocyte cells including higher expression of several hepatocyte-specific genes such as ALB and some CYP450, lower expression of AFP and positive glycogen expression (P <  .05) in coculturing with human hepatocyte L02 cells for 10-15d.

CONCLUSIONS

HUSCs can be induced to differentiate into hepatocyte-like cells by coculturing with human hepatocyte L02 cells for a certain number of days.

A combination of ultrasound-targeted microbubble destruction with transplantation of bone marrow mesenchymal stem cells promotes recovery of acute liver injury

Background

Bone marrow mesenchymal stem cells (BMSCs) can provide an additional source of therapeutic stem cells for regeneration of liver cells during acute liver injury (ALI). However, the insufficient hepatic homing by the transplanted BMSCs limits their applications. Ultrasound-targeted microbubble destruction (UTMD) has been reported to promote the homing of transplanted stem cells into the ischemic myocardium. In this study, we investigated whether UTMD promotes the hepatic homing of BMSCs in ALI rats and evaluated the therapeutic effect.

Methods

BMSCs were isolated from the femurs and tibias of Sprague-Dawley (SD) rats. The isolated BMSCs were stably transfected with a lentivirus expressing enhanced green fluorescent protein (EGFP) that can be visualized and quantified in vivo after transplantation. Both tumor necrosis factor α (TNF-α) and stromal cell-derived factor 1 (SDF-1) were used to verify the appropriate ultrasound parameters. The ALI rats were divided into four groups: control, BMSCs, UTMD, and UTMD + BMSCs. The protein and mRNA expression levels of SDF-1, intercellular cell adhesion molecule (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), hepatocyte growth factor (HGF), and monocyte chemotactic protein 1 (MCP-1) in the exposed livers were analyzed at 48 h after treatment. ALI recovery was determined by serum biochemical parameters and histology.

Results

The isolated rat BMSCs demonstrated a good proliferation potential that was both osteogenic and adipogenic in differentiation and expressed cluster of differentiation (CD) 29 and CD90, but not CD45 or CD11b/c. After BMSC and/or UTMD treatment, the number of GFP-labeled BMSCs in the UTMD + BMSCs group was significantly higher than that of the BMSCs group (9.8 ± 2.3 vs. 5.2 ± 1.1/per high-power field). Furthermore, the expression of GFP mRNA was performed for evaluation of the homing rate of BMSCs in injury sites as well. In addition, the expression levels of SDF-1, ICAM-1, VCAM-1, HGF, and MCP-1 were higher (p < 0.01) in UTMD+BMSCs group. The serum levels of biomarkers were significantly lower in the UTMD + BMSCs group, and the apoptotic rate of hepatocytes in the UTMD + BMSCs group was markedly lower than that of the BMSCs group (all p < 0.05). The hepatic pathology was significantly alleviated in the UTMD + BMSCs group.

Conclusions

UTMD treatment efficiently induced a favorable microenvironment for cell engraftment, resulting in improvement of hepatic homing of BMSCs, which was probably mediated through upregulation of the expression of adhesion molecules and cytokines. UTMD treatment appeared to be an effective and noninvasive approach to achieve better efficacy of BMSC-based therapy for repairing a severely injured liver.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1098-4) contains supplementary material, which is available to authorized users.