Monitoring transplanted adipose tissue-derived stem cells combined with heparin in the liver by fluorescence imaging using quantum dots. Biomaterials. 2012;33:2177-2186. [PMID: 22192539 DOI: 10.1016/j.biomaterials.2011.12.009]

Mesenchymal Stem Cells-Involved Strategies for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints and bone destruction. Because of systemic administration and poor targeting, traditional anti-rheumatic drugs have unsatisfactory treatment efficacy and strong side effects, including myelosuppression, liver or kidney function damage, and malignant tumors. Consequently, mesenchymal stem cells (MSCs)-involved therapy is proposed for RA therapy as a benefit of their immunosuppressive and tissue-repairing effects. This review summarizes the progress of MSCs-involved RA therapy through suppressing inflammation and promoting tissue regeneration and predicts their potential clinical application.

Stem cell therapy for cardiac regeneration: past, present, and future

Cardiac disorders remain the leading cause of mortality worldwide. Current clinical strategies, including drug therapy, surgical interventions, and organ transplantation offer limited benefits to patients without regenerating the damaged myocardium. Over the past decade, stem cell therapy has generated a keen interest owing to its unique self-renewal and immune privileged characteristics. Furthermore, the ability of stem cells to differentiate into specialized cell types, has made them a popular therapeutic tool against various diseases. This comprehensive review provides an overview of therapeutic potential of different types of stem cells in reference to cardiovascular diseases. Furthermore, it sheds light on the advantages and limitations associated with each cell type. An in-depth analysis of the challenges associated with stem cell research and the hurdles for its clinical translation and their possible solutions have also been elaborated upon. It examines the controversies surrounding embryonic stem cells and the emergence of alternative approaches, such as the use of induced pluripotent stem cells for cardiac therapeutic applications. Overall, this review serves as a valuable resource for researchers, clinicians, and policymakers involved in the field of regenerative medicine, guiding the development of safe and effective stem cell-based therapies to revolutionize patient care.

Nanocrystals for Deep-Tissue In Vivo Luminescence Imaging in the Near-Infrared Region

In vivo imaging technologies have emerged as a powerful tool for both fundamental research and clinical practice. In particular, luminescence imaging in the tissue-transparent near-infrared (NIR, 700-1700 nm) region offers tremendous potential for visualizing biological architectures and pathophysiological events in living subjects with deep tissue penetration and high imaging contrast owing to the reduced light-tissue interactions of absorption, scattering, and autofluorescence. The distinctive quantum effects of nanocrystals have been harnessed to achieve exceptional photophysical properties, establishing them as a promising category of luminescent probes. In this comprehensive review, the interactions between light and biological tissues, as well as the advantages of NIR light for in vivo luminescence imaging, are initially elaborated. Subsequently, we focus on achieving deep tissue penetration and improved imaging contrast by optimizing the performance of nanocrystal fluorophores. The ingenious design strategies of NIR nanocrystal probes are discussed, along with their respective biomedical applications in versatile in vivo luminescence imaging modalities. Finally, thought-provoking reflections on the challenges and prospects for future clinical translation of nanocrystal-based in vivo luminescence imaging in the NIR region are wisely provided.

Nanoghosts: Harnessing Mesenchymal Stem Cell Membrane for Construction of Drug Delivery Platforms Via Optimized Biomimetics

Mesenchymal stem cells (MSCs) are becoming hotspots for application in disease therapies recently, combining with biomaterials and drug delivery system. A major advantage of MSCs applied in drug delivery system is that these cells enable specific targeting and releasing of cargos to the disease sites. However, the potential tumor tropic effects of MSCs raised concerns on biosafety. To solve this problem, there are emerging methods of isolating cell membranes and developing nanoformulations to perform drug delivery, which avoids concerns on biosafety without disturbing the membrane functions of specific polarizing and locating. These cargoes are so called "nanoghosts." This review article summarizes the current applications of nanoghosts, the promising potential of MSCs to be applied in membrane isolation and nanoghost construction, and possible approaches to develop better drug delivery system harnessing from MSC ghost cell membranes.

Human Mesenchymal Stem Cells and Innovative Scaffolds for Bone Tissue Engineering Applications

Stem cell-based therapy is a significant topic in regenerative medicine, with a predominant role being played by human mesenchymal stem cells (hMSCs). The hMSCs have been shown to be suitable in regenerative medicine for the treatment of bone tissue. In the last few years, the average lifespan of our population has gradually increased. The need of biocompatible materials, which exhibit high performances, such as efficiency in bone regeneration, has been highlighted by aging. Current studies emphasize the benefit of using biomimetic biomaterials, also known as scaffolds, for bone grafts to speed up bone repair at the fracture site. For the healing of injured bone and bone regeneration, regenerative medicine techniques utilizing a combination of these biomaterials, together with cells and bioactive substances, have drawn a great interest. Cell therapy, based on the use of hMSCs, alongside materials for the healing of damaged bone, has obtained promising results. In this work, several aspects of cell biology, tissue engineering, and biomaterials applied to bone healing/regrowth will be considered. In addition, the role of hMSCs in these fields and recent progress in clinical applications are discussed. Impact Statement The restoration of large bone defects is both a challenging clinical issue and a socioeconomic problem on a global scale. Different therapeutic approaches have been proposed for human mesenchymal stem cells (hMSCs), considering their paracrine effect and potential differentiation into osteoblasts. However, different limitations are still to be overcome in using hMSCs as a therapeutic opportunity in bone fracture repair, including hMSC administration methods. To identify a suitable hMSC delivery system, new strategies have been proposed using innovative biomaterials. This review provides an update of the literature on hMSC/scaffold clinical applications for the management of bone fractures.

Efficient delivery of mesenchymal stem/stromal cells to injured liver by surface PEGylation

BACKGROUND

Mesenchymal stem/stromal cells (MSCs) have been used in clinical trials for various diseases. These have certain notable functions such as homing to inflammation sites, tissue repair, and immune regulation. In many pre-clinical studies, MSCs administered into peripheral veins demonstrated effective therapeutic outcomes. However, most of the intravenously administered MSCs were entrapped in the lung, and homing to target sites was less than 1%. This occurred mainly because of the adhesion of MSCs to vascular endothelial cells in the lung. To prevent this adhesion, we modified the surface of MSCs with polyethylene glycol (PEG; a biocompatible polymer) using the avidin-biotin complex (ABC) method.

METHODS

The surface of MSCs was modified with PEG using the ABC method. Then, the cell adhesion to mouse aortic endothelial cells and the tissue distribution of PEG-modified MSCs were evaluated. Moreover, the homing to the injured liver and therapeutic effect of PEG-modified MSCs were evaluated using carbon tetrachloride-induced acute liver failure model mice.

RESULTS

The PEG modification significantly suppressed the adhesion of MSCs to cultured mouse aortic endothelial cells as well as the entrapment of MSCs in the lungs after intravenous injection in mice. PEG-modified MSCs efficiently homed to the injured liver of carbon tetrachloride-induced acute liver failure model mice. More importantly, the cells significantly suppressed serum transaminase levels and leukocyte infiltration into the injured liver.

CONCLUSION

These results indicate that PEG modification to the surface of MSCs can suppress the lung entrapment of intravenously administered MSCs and improve their homing to the injured liver.

Acute liver failure: A systematic review and network meta-analysis of optimal type of stem cells in animal models

BACKGROUND

The therapeutic effects of various stem cells in acute liver failure (ALF) have been demonstrated in preclinical studies. However, the specific type of stem cells with the highest therapeutic potential has not been determined.

AIM

To validate the efficacy of stem cells in ALF model and to identify the most promising stem cells.

METHODS

A search was conducted on the PubMed, Web of Science, Embase, Scopus, and Cochrane databases from inception to May 3, 2022, and updated on November 16, 2022 to identify relevant studies. Two independent reviewers performed the literature search, identification, screening, quality assessment, and data extraction.

RESULTS

A total of 89 animal studies were included in the analysis. The results of traditional meta-analysis showed that stem cell therapy could significantly reduce the serum levels of alanine aminotransferase [weighted mean difference (WMD) = -181.05 (-191.71, -170.39)], aspartate aminotransferase [WMD = -309.04 (-328.45, -289.63)], tumor necrosis factor-alpha [WMD = -8.75 (-9.93, -7.56)], and interleukin-6 [WMD = -10.43 (-12.11, -8.76)] in animal models of ALF. Further subgroup analysis and network meta-analysis showed that although mesenchymal stem cells are the current research hotspot, the effect of liver stem cells (LSCs) on improving liver function is significantly better than that of the other five types of stem cells. In addition, the ranking results showed that the possibility of LSCs improving liver function ranked first. This fully proves the great therapeutic potential of LSCs, which needs to be paid more attention in the future.

CONCLUSION

LSCs may have a higher therapeutic potential. Further high-quality animal experiments are needed to explore the most effective stem cells for ALF.

Multifunctional Magnetic CuS/Gd2O3 Nanoparticles for Fluorescence/Magnetic Resonance Bimodal Imaging-Guided Photothermal-Intensified Chemodynamic Synergetic Therapy of Targeted Tumors

Chemodynamic therapy (CDT), which consumes endogenous hydrogen peroxide (H₂O₂) to generate reactive oxygen species (ROS) and causes oxidative damage to tumor cells, shows tremendous promise for advanced cancer treatment. However, the rate of ROS generation based on the Fenton reaction is prone to being restricted by inadequate H₂O₂ and unattainable acidity in the hypoxic tumor microenvironment. We herein report a multifunctional nanoprobe (BCGCR) integrating bimodal imaging and photothermal-enhanced CDT of the targeted tumor, which is produced by covalent conjugation of bovine serum albumin-stabilized CuS/Gd₂O₃ nanoparticles (NPs) with the Cy5.5 fluorophore and the tumor-targeting ligand RGD. BCGCR exhibits intense near-infrared (NIR) fluorescence and acceptable r₁ relaxivity (∼15.3 mM^-1 s^-1) for both sensitive fluorescence imaging and high-spatial-resolution magnetic resonance imaging of tumors in living mice. Moreover, owing to the strong NIR absorbance from the internal CuS NPs, BCGCR can generate localized heat and displays a high photothermal conversion efficiency (30.3%) under 980 nm laser irradiation, which enables photothermal therapy and further intensifies ROS generation arising from the Cu-induced Fenton-like reaction for enhanced CDT. This synergetic effect shows such an excellent therapeutic efficacy that it can ablate xenografted tumors in vivo. We believe that this strategy will be beneficial to exploring other advanced nanomaterials for the clinical application of multimodal imaging-guided synergetic cancer therapies.

Fluorescent/magnetic nano-aggregation via electrostatic force between modified quantum dot and iron oxide nanoparticles for bimodal imaging of U87MG tumor cells

Imaging technology based on novel nanomaterials is burgeoning as a potential tool for exploring various physiological processes. We herein report a fluorescent and magnetic nanoprobe (QMNP-RGD) for bimodal imaging of in vitro tumor cells. The preparation of this multifunctional nanomaterial is divided into three steps. First, commercial quantum dots (QDs) with high fluorescence intensity are covalently modified with an RGD peptide, which can facilitate the tumor cell uptake by α_vβ₃ integrin-induced active recognition. Superparamagnetic iron oxide (SPIO) nanoparticles (NPs) are then capped using a cationic polysaccharide to improve stability. Integration is finally achieved by convenient electrostatic binding. We successfully demonstrated that QMNP-RGD can be efficiently delivered into U87MG cells and used for fluorescence/magnetic resonance (MR) bimodal imaging. Other multimodal probes may be able to be designed for imaging based on this strategy of electrostatic binding.

Micro-/nano-fluidic devices and in vivo fluorescence imaging based on quantum dots for cytologic diagnosis

Semiconductor quantum dots (QDs) possess attractive merits over traditional organic dyes, such as tunable emission, narrow emission spectra and good resistance against optical bleaching, and play a vital role in biosensing and bioimaging for cytologic diagnoses. Microfluidic technology is a potentially useful strategy, as it provides a rapid platform for tracing of disease markers. In vivo fluorescence imaging (FI) based on QDs has become popular for the analysis of complex biological processes. We herein report the applications of multifunctional fluorescent QDs as sensitive probes for diagnoses on cancer medicine and stem cell therapy via microfluidic chips and in vivo imaging.

Mesenchymal stem cells: A living carrier for active tumor-targeted delivery

The strategy of using mesenchymal stem cells (MSCs) as a living carrier for active delivery of therapeutic agents targeting tumor sites has been attempted in a wide range of studies to validate the feasibility and efficacy for tumor treatment. This approach reveals powerful tumor targeting and tumor penetration. In addition, MSCs have been confirmed to actively participate in immunomodulation of the tumor microenvironment. Thus, MSCs are not inert delivery vehicles but have a strong impact on the fate of tumor cells. In this review, these active properties of MSCs are addressed to highlight the advantages and challenges of using MSCs for tumor-targeted delivery. In addition, some of the latest examples of using MSCs to carry a variety of anti-tumor agents for tumor-targeted therapy are summarized. Recent technologies to improve the performance and safety of this delivery strategy will be introduced. The advances, applications, and challenges summarized in this review will provide a general understanding of this promising strategy for actively delivering drugs to tumor tissues.

Mesenchymal stem cell homing to improve therapeutic efficacy in liver disease

Mesenchymal stem cell (MSC) transplantation, as an alternative strategy to orthotopic liver transplantation, has been evaluated for treating end-stage liver disease. Although the therapeutic mechanism of MSC transplantation remains unclear, accumulating evidence has demonstrated that MSCs can regenerate tissues and self-renew to repair the liver through differentiation into hepatocyte-like cells, immune regulation, and anti-fibrotic mechanisms. Multiple clinical trials have confirmed that MSC transplantation restores liver function and alleviates liver damage. A sufficient number of MSCs must be home to the target tissues after administration for successful application. However, inefficient homing of MSCs after systemic administration is a major limitation in MSC therapy. Here, we review the mechanisms and clinical application status of MSCs in the treatment of liver disease and comprehensively summarize the molecular mechanisms of MSC homing, and various strategies for promoting MSC homing to improve the treatment of liver disease.

Mesenchymal Stem/Stromal Cells and Their Paracrine Activity-Immunomodulation Mechanisms and How to Influence the Therapeutic Potential

With high clinical interest to be applied in regenerative medicine, Mesenchymal Stem/Stromal Cells have been widely studied due to their multipotency, wide distribution, and relative ease of isolation and expansion in vitro. Their remarkable biological characteristics and high immunomodulatory influence have opened doors to the application of MSCs in many clinical settings. The therapeutic influence of these cells and the interaction with the immune system seems to occur both directly and through a paracrine route, with the production and secretion of soluble factors and extracellular vesicles. The complex mechanisms through which this influence takes place is not fully understood, but several functional manipulation techniques, such as cell engineering, priming, and preconditioning, have been developed. In this review, the knowledge about the immunoregulatory and immunomodulatory capacity of MSCs and their secretion products is revisited, with a special focus on the phenomena of migration and homing, direct cell action and paracrine activity. The techniques for homing improvement, cell modulation and conditioning prior to the application of paracrine factors were also explored. Finally, multiple assays where different approaches were applied with varying success were used as examples to justify their exploration.

Cliv-92-Loaded Glycyrrhetinic Acid-Modified Chitosan Nanoparticles for Enhanced Hepatoprotection-Preparation, Characterization, and In Vivo Evaluation

Cliv-92 is a mixture of three structurally similar coumarinolignoids and a proven hepatoprotective agent. Low aqueous solubility and poor bioavailability are notable hindrances for its further use. Therefore, glycyrrhetinic acid-linked chitosan nanoparticles loaded with Cliv-92 were prepared for active targeting to the liver. The nanoparticles were prepared by the ionic gelation method to avoid the use of toxic solvents/rigorous agitation. The method of preparation was optimized using a central composite design with independent variables, namely polymer: drug ratio (3:1, w/w), crosslinker concentration (0.5%), and stirring speed (750 rpm). The optimized nanoparticles had a mean particle size of 185.17 nm, a polydispersity index of 0.41, a zeta potential of 30.93 mV, and a drug loading of 16.30%. The prepared formulation showed sustained release of approximately 63% of loaded Cliv-92 over 72 h. The nanoparticles were freeze-dried for long-term storage and further characterized. The formulation was found to be biocompatible for parenteral delivery. In vivo imaging study showed that optimized nanoparticles were preferentially accumulated in the liver and successfully targeting the liver. The present study successfully demonstrated the improved pharmacokinetic properties (≈12% relative bioavailability) and efficacy profile (evidenced by in vivo and histopathological studies) of fabricated Cliv-92 nanoparticles.

Application of Mesenchymal Stem Cells in Targeted Delivery to the Brain: Potential and Challenges of the Extracellular Vesicle-Based Approach for Brain Tumor Treatment

Treating brain tumors presents enormous challenges, and there are still poor prognoses in both adults and children. Application of novel targets and potential drugs is hindered by the function of the blood-brain barrier, which significantly restricts therapeutic access to the tumor. Mesenchymal stem cells (MSCs) can cross biological barriers, migrate to sites of injuries to exert many healing effects, and be engineered to incorporate different types of cargo, making them an ideal vehicle to transport anti-tumor agents to the central nervous system. Extracellular vesicles (EVs) produced by MSCs (MSC-EVs) have valuable innate properties from parent cells, and are being exploited as cell-free treatments for many neurological diseases. Compared to using MSCs, targeted delivery via MSC-EVs has a better pharmacokinetic profile, yet avoids many critical issues of cell-based systems. As the field of MSC therapeutic applications is quickly expanding, this article aims to give an overall picture for one direction of EV-based targeting of brain tumors, with updates on available techniques, outcomes of experimental models, and critical challenges of this concept.

Mesenchymal Stem Cell Therapy for Acetaminophen-Related Liver Injury: A Systematic Review and Meta-Analysis of Experimental Studies in Vivo

OBJECTIVE

The efficacy of mesenchymal stem cell (MSC) therapy in acetaminophen-induced liver injury has been investigated in animal experiments, but individual studies with a small sample size cannot be used to draw a clear conclusion. Therefore, we conducted a systematic review and meta-analysis of preclinical studies to explore the potential of using MSCs in acetaminophen-induced liver injury.

METHODS

Eight databases were searched for studies reporting the effects of MSCs on acetaminophen hepatoxicity. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used. SYRCLE's risk of bias tool for animal studies was applied to assess the methodological quality. A meta-analysis was performed by using RevMan 5.4 and STATA/SE 16.0 software.

RESULTS

Eleven studies involving 159 animals were included according to PRISMA statement guidelines. Significant associations were found for MSCs with the levels of alanine transaminase (ALT) (standardized mean difference (SMD) - 2.58, p < 0.0001), aspartate aminotransferase (AST) (SMD - 1.75, p = 0.001), glutathione (GSH) (SMD 3.7, p < 0.0001), superoxide dismutase (SOD) (SMD 1.86, p = 0.022), interleukin 10 (IL-10) (SMD 5.14, p = 0.0002) and tumor necrosis factor-α (TNF-α) (SMD - 4.48, p = 0.011) compared with those in the control group. The subgroup analysis showed that the tissue source of MSCs significantly affected the therapeutic efficacy (p < 0.05).

CONCLUSION

Our meta-analysis results demonstrate that MSCs could be a potential treatment for acetaminophen-related liver injury.

Impact of Human Umbilical Cord Blood Mononuclear Cells on Gentamicin-Induced Renal Injury and Genotoxicity in Rats

Background: Acute kidney injury (AKI), also known as acute renal failure (ARF), has received considerable critical attention in recent years. Gentamicin (GM) is an antibiotic whose prolonged use results in AKI with a high mortality rate.

Methods: Fifty adult female albino rats weighing 150–200 g were used. The animals were divided into five groups: the first group was the normal healthy control one, the second group received only 1 × 10⁶ HUCB mononuclear cells (MNCs)/rat by intravenous (iv) injection, the third diseased group was given GM 100 mg/kg for 10 consecutive days by intraperitoneal injections, the fourth preventive group received 1 × 10⁶ HUCB MNCs/rat by iv injection 24 h before gentamicin treatment, and the fifth treated group received 1 × 10⁶ HUCB MNCs/rat by iv injection 24 h after gentamicin treatment. After 1 week of treatment, blood samples were collected, and kidneys were removed for histopathological examination.

Results: Rats treated with HUCB MNCs in the treated group had a significant decrease in renal damage, low levels of biomarkers for nephrotoxicities such as serum creatinine and blood urea nitrogen, and low chromosomal aberrations compared to the diseased third group. The gene expression of KIM-1 and NGAL was decreased in response to HUCB treatment.

Conclusions: HUCB MNCs have a curative effect against AKI and gentamicin-induced genotoxicity owing to their regenerative property.

Mesenchymal stem cells from biology to therapy

Mesenchymal stem cells are as fascinating as they are enigmatic. They appear capable of performing a wide array of functions that cross skeletal biology, immunology and haematology. As therapeutics, mesenchymal stem cells or even just their secreted products may be used to regenerate tissue lost through injury or disease and suppress damaging immune reactions. However, these cells lack unique markers and are hard to identify and isolate as pure cell populations. They are often grown in laboratories using basic and undefined culture conditions. We cannot even agree on their name. While mesenchymal stem cells may lack the developmental understanding and defined differentiation hierarchies of their more illustrious stem cell cousins, they offer a compelling scientific challenge. In depth understanding of mesenchymal stem cell biology will enable us to exploit fully one of the most clinically valuable cell sources.

Detection and quantification of human-specific mRNA from hepatocyte-like cells derived from dental pulp using real-time polymerase chain reaction

OBJECTIVES

We quantified viable hepatocyte-like cells (HLCs) administered via portal or tail veins in the livers and lungs of immunodeficient rats using real-time reverse transcription polymerase chain reaction (RT-PCR) and human glyceraldehyde 3-phosphate dehydrogenase (GAPDH) primers.

METHODS

Immunodeficient rats were infused with HLCs via portal or tail veins. mRNA was quantified based on the route of cell administration and the presence of liver injury.

RESULTS

Human-specific GAPDH mRNA primers detected 0.1 pg human RNA in 100 ng (1:10⁶) of rat liver RNA. When infused into the portal vein, the quantity of HLC mRNA reduced to 5% 3 hours after infusion. Most HLCs were entrapped in the lungs when infused via the tail vein and decreased to approximately 10% 6 hours after infusion. A small number of HLCs made it to the liver but disappeared rapidly, regardless of liver injury. 24 hours after infusion, viable HLCs were detected only in the lungs of rats with liver injury (P < 0.05).

CONCLUSIONS

The quantity of viable human cells in immunodeficient rats was estimated using real-time RT-PCR and primers specific to human mRNA.

Biological, chemical and mechanical factors regulating migration and homing of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are a population of primary and non-specialized cells, which can be isolated from various tissues. Currently, MSCs are key players in cellular therapy and regenerative medicine. However, the possibility of using MSCs in the treatment of many diseases needs to be preceded, though, by in-depth analysis of their properties, especially by determining the mechanism of tissue homing as well as the mechanism, due to which cells contribute to tissue regeneration. This review is intended to present information on recent findings regarding the mechanism of recruitment and tissue homing by MSCs and discuss current hypotheses for how MSCs can reach target tissues.

Mesenchymal Stromal Cells and Their Secretome: New Therapeutic Perspectives for Skeletal Muscle Regeneration

Mesenchymal stromal cells (MSCs) are multipotent cells found in different tissues: bone marrow, peripheral blood, adipose tissues, skeletal muscle, perinatal tissues, and dental pulp. MSCs are able to self-renew and to differentiate into multiple lineages, and they have been extensively used for cell therapy mostly owing to their anti-fibrotic and immunoregulatory properties that have been suggested to be at the basis for their regenerative capability. MSCs exert their effects by releasing a variety of biologically active molecules such as growth factors, chemokines, and cytokines, either as soluble proteins or enclosed in extracellular vesicles (EVs). Analyses of MSC-derived secretome and in particular studies on EVs are attracting great attention from a medical point of view due to their ability to mimic all the therapeutic effects produced by the MSCs (i.e., endogenous tissue repair and regulation of the immune system). MSC-EVs could be advantageous compared with the parental cells because of their specific cargo containing mRNAs, miRNAs, and proteins that can be biologically transferred to recipient cells. MSC-EV storage, transfer, and production are easier; and their administration is also safer than MSC therapy. The skeletal muscle is a very adaptive tissue, but its regenerative potential is altered during acute and chronic conditions. Recent works demonstrate that both MSCs and their secretome are able to help myofiber regeneration enhancing myogenesis and, interestingly, can be manipulated as a novel strategy for therapeutic interventions in muscular diseases like muscular dystrophies or atrophy. In particular, MSC-EVs represent promising candidates for cell free-based muscle regeneration. In this review, we aim to give a complete picture of the therapeutic properties and advantages of MSCs and their products (MSC-derived EVs and secreted factors) relevant for skeletal muscle regeneration in main muscular diseases.

Biomimetic Culture Strategies for the Clinical Expansion of Mesenchymal Stromal Cells

Mesenchymal stromal/stem cells (MSCs) typically require significant ex vivo expansion to achieve the high cell numbers required for research and clinical applications. However, conventional MSC culture on planar (2D) plastic surfaces has been shown to induce MSC senescence and decrease cell functionality over long-term proliferation, and usually, it has a high labor requirement, a high usage of reagents, and therefore, a high cost. In this Review, we describe current MSC-based therapeutic strategies and outline the important factors that need to be considered when developing next-generation cell expansion platforms. To retain the functional value of expanded MSCs, ex vivo culture systems should ideally recapitulate the components of the native stem cell microenvironment, which include soluble cues, resident cells, and the extracellular matrix substrate. We review the interplay between these stem cell niche components and their biological roles in governing MSC phenotype and functionality. We discuss current biomimetic strategies of incorporating biochemical and biophysical cues in MSC culture platforms to grow clinically relevant cell numbers while preserving cell potency and stemness. This Review summarizes the current state of MSC expansion technologies and the challenges that still need to be overcome for MSC clinical applications to be feasible and sustainable.

CT/NIRF dual-modal imaging tracking and therapeutic efficacy of transplanted mesenchymal stem cells labeled with Au nanoparticles in silica-induced pulmonary fibrosis

Mesenchymal stem cells (MSCs) have shown promising therapeutic effects in cell-based therapies and regenerative medicine. Efficient tracking of MSCs is an urgent clinical need that will help us to understand their behavior after transplantation and allow adjustment of therapeutic strategies. However, no clinically approved tracers are currently available, which limits the clinical translation of stem cell therapy. In this study, a nanoparticle (NP) for computed tomography (CT)/fluorescence dual-modal imaging, Au@Albumin@ICG@PLL (AA@ICG@PLL), was developed to track bone marrow-derived mesenchymal stem cells (BMSCs) that were administered intratracheally into mice with silica-induced pulmonary fibrosis, which facilitated understanding of the therapeutic effect and the possible molecular mechanism of stem cell therapy. The AuNPs were first formed in bovine serum albumin (BSA) solution and modified with indocyanine green (ICG), and subsequently coated with a poly-l-lysine (PLL) layer to enhance intracellular uptake and biocompatibility. BMSCs were labeled with AA@ICG@PLL NPs with high efficiency without an effect on biological function or therapeutic capacity. The injected AA@ICG@PLL-labeled BMSCs could be tracked via CT and near-infrared fluorescence (NIRF) imaging for up to 21 days after transplantation. Using these NPs, the molecular anti-inflammatory mechanism of transplanted BMSCs was revealed, which included the downregulation of proinflammatory cytokines, suppression of macrophage activation, and delay of the fibrosis process. This study suggests a promising role for imaging-guided MSC-based therapy for pulmonary fibrosis, such as idiopathic pulmonary fibrosis (IPF) and pneumoconiosis.

Sandwich-Type Near-Infrared Conjugated Polymer Nanoparticles for Revealing the Fate of Transplanted Human Umbilical Cord Mesenchymal Stem Cells

Near-infrared conjugated polymer nanoparticles (NIR-CPNs) have been widely used in in vivo imaging fields. However, most of them face the aggregation-induced fluorescence quenching (ACQ) dilemma and serious dye leakage behavior, which impedes the long-term monitoring of transplanted cells in vivo. In the present work, a novel strategy of sandwich-type encapsulation of the conjugated polymer interlayer in the crystalline SiO2 core + shell (SSiO2@SPFTBT@CSiO2) is developed, which works well to avoid the ACQ problem by homogeneously dispersing poly((9,9-dioctylfluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5',5″-diyl) (PFTBT) and suppressing intermolecular π-π stacking. Furthermore, the unparalleled nanostructure efficiently stabilizes nanoparticles and successfully achieves long-term biocompatibility without interfering the biological characteristics of stem cells, indicating the potential of SSiO2@SPFTBT@CSiO2 in cell labeling. In addition, the fate of human umbilical cord mesenchymal stem cells (hucMSCs) in a mouse model with acute liver injury was disclosed. We found that the hucMSCs mainly migrated from the lungs to the injured liver and most transplanted hucMSCs were cleared up by the liver at 8 days post-injection. Revelation of the shuttle process and period will benefit in improving the clinical efficacy of hucMSCs, and the sandwich-type encapsulation strategy could also open a new avenue to obtain bright and robust NIR-CPNs for long-term fluorescence imaging.

Whole-Body Fluorescence Imaging in the Near-Infrared Window

Fluorescence imaging is one of the most widely used in vivo imaging methods for both fundamental research and clinical practice. Due to the reduced photon scattering, absorption, and autofluorescence in tissues, the emerging near-infrared (NIR) imaging (650-1700 nm) can afford deep tissue imaging with high spatiotemporal resolution and in vivo report the anatomical structures as well as the physiological activities in a whole-body level. Here, we give a brief introduction to fluorescence imaging in the first NIR (NIR-I, 650-950 nm) and second NIR (NIR-II, 1000-1700 nm) windows, summarize the recently developed NIR fluorophores and their applications in whole-body vascular system imaging, precision cancer theranostics, and regenerative medicine. Finally, the clinical applications and future prospects of in vivo NIR fluorescence imaging are also discussed.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Extracellular Vesicle-Dependent Communication Between Mesenchymal Stromal Cells and Immune Effector Cells

Mesenchymal stem/stromal cells (MSCs) are multipotent cells residing in the stromal tissues of the body and capable of promoting tissue repair and attenuating inflammatory processes through their immunomodulatory properties. Preclinical and clinical observations revealed that not only direct intercellular communication mediates MSC properties; in fact, a pivotal role is also played by the release of soluble and bioactive factors, such as cytokines, growth factor and extracellular vesicles (EVs). EVs are membrane-coated vesicles containing a large variety of bioactive molecules, including lipids, proteins, and nucleic acids, such as RNA. EVs release their contents into target cells, thus influencing cell fate through the control of intracellular processes. In addition, MSC-derived EVs can mediate modulatory effects toward different effector cells belonging to both innate and adaptive immunity. In this review, we will discuss the literature data concerning MSC-derived EVs, including the current standardized methods for their isolation and characterization, the mechanisms supporting their immunoregulatory properties, and their potential clinical application as alternative to MSC-based therapy for inflammatory reactions, such as graft-versus-host disease (GvHD).

Adipose stem cells exhibit mechanical memory and reduce fibrotic contracture in a rat elbow injury model

Fibrosis is driven by a misdirected cell response causing the overproduction of extracellular matrix and tissue dysfunction. Numerous pharmacological strategies have attempted to prevent fibrosis but have attained limited efficacy with some detrimental side effects. While stem cell treatments have provided more encouraging results, they have exhibited high variability and have not always improved tissue function. To enhance stem cell efficacy, we evaluated whether mechanical memory could direct cell response. We hypothesized that mechanically pre-conditioning on a soft matrix (soft priming) will delay adipose-derived stem cell (ASC) transition to a pro-fibrotic phenotype, expanding their regenerative potential, and improving healing in a complex tissue environment. Primary ASCs isolated from rat and human subcutaneous fat exhibited mechanical memory, demonstrated by a delayed cell response to stiffness following two weeks of soft priming including decreased cell area, actin coherency, and extracellular matrix production compared to cells on stiff substrates. Soft primed ASCs injected into our rat model of post-traumatic elbow contracture decreased histological evidence of anterior capsule fibrosis and increased elbow range-of-motion when evaluated by joint mechanics. These findings suggest that exploiting mechanical memory by strategically controlling the culture environment during cell expansion may improve the efficacy of stem cell-based therapies targeting fibrosis.

A quantum thermometric sensing and analysis system using fluorescent nanodiamonds for the evaluation of living stem cell functions according to intracellular temperature

Intracellular thermometry techniques play an important role in elucidating the relationship between the intracellular temperature and stem cell functions. However, there have been few reports on thermometry techniques that can detect the intracellular temperature of cells during several days of incubation. In this study, we developed a novel quantum thermometric sensing and analysis system (QTAS) using fluorescent nanodiamonds (FNDs). FNDs could label adipose tissue-derived stem cells (ASCs) at high efficiency with 24 h of incubation, and no cytotoxicity was observed in ASCs labeled with less than 500 μg mL^-1 of FNDs. The peak of FNDs was confirmed at approximately 2.87 GHz with the characteristic fluorescence spectra of NV centers that could be optically detected (optically detected magnetic resonance [ODMR]). The ODMR peak clearly shifted to the high-frequency side as the temperature decreased and gave a mean temperature dependence of -(77.6 ± 11.0) kHz °C^-1, thus the intracellular temperature of living ASCs during several days of culturing could be precisely measured using the QTAS. Moreover, the intracellular temperature was found to influence the production of growth factors and the degree of differentiation into adipocytes and osteocytes. These data suggest that the QTAS can be used to investigate the relationship between intracellular temperature and cellular functions.

Co-Incorporated Mesoporous Carbon Material-Assisted Laser Desorption/Ionization Ion Source as an Online Interface of In Vivo Microdialysis Coupled with Mass Spectrometry

The combination of microdialysis and mass spectrometry (MS) provides the potential for rapidly monitoring diverse metabolites in vivo. Unfortunately, the high concentration of salt in biological microdialysates hindered the sensitive and online detection of these small molecular compounds. In this study, we synthesized Co-incorporated mesoporous carbon material (Co-NC) and developed a Co-NC-assisted laser desorption/ionization (LDI) ion source as an online interface of in vivo microdialysis coupled with MS for the direct analysis of diverse metabolites in microdialysates. The Co-NC could be used as a matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) analysis of small molecular compounds, even under high concentration salt conditions. The Co-NC possessed the adsorption ability for small molecular compounds, and it was believed that the adsorption ability of Co-NC might separate the analytes from the salt in microdialysates at a microscopic level, which might facilitate the desorption and ionization of the analytes and finally improved the salt-tolerance ability as a matrix. Furthermore, the Co-NC-assisted LDI ion source as a novel interface of in vivo microdialysis coupled with MS has been applied to the online monitoring of liver metabolites from the CCl₄-induced liver injury rat model for the first time.

Copper promotes migration of adipose-derived stem cells by enhancing vimentin-Ser39 phosphorylation

Mesenchymal stem cells (MSCs) are widely studied for their application in cell therapy. A noticed drawback of these cells in response to tissue injury is the low efficiency of homing. The present study was undertaken to explore a possible approach to promote the migration of MSCs. Primary cultures of rat adipose-derived stem cells (rADSCs) were cultured in standard L-DMEM media supplemented with or without copper (Cu) at its final concentration of 20 μM in cultures. The analyses of transwell and wound-healing assay revealed that Cu supplementation significantly promotes the migration of rADSCs in cultures. Further analysis found that Cu stimulated the phosphorylation of vimentin Ser39. Point mutation of vimentin Ser39 by substituting Ser with Ala prevented Cu-promoted migration of rADSCs. This study thus demonstrates that Cu promotes migration of rADSCs in cultures through at least in part Cu stimulation of vimentin Ser39 phosphorylation.

Visualizing the Fate of Intra-Articular Injected Mesenchymal Stem Cells In Vivo in the Second Near-Infrared Window for the Effective Treatment of Supraspinatus Tendon Tears

Mesenchymal stem cells (MSCs) are capable of exerting strong therapeutic potential for the treatment of supraspinatus tendon tear. However, MSC therapy remains underutilized and perhaps underrated due to the limited evidence of dynamic visualization of cellular behavior in vivo. Here, second near-infrared fluorescence imaging with biocompatible PbS quantum dots (QDs) provides a cellular migration map and information on the biodistribution and clearance processes of three densities of intra-articularly injected, labeled MSCs to treat supraspinatus tendon tear in mice. Intra-articular injection avoids entrapment of MSCs by filter organs and reduces the QD-induced organ toxicity. Notably, the MSCs share a similar migration direction, but the moderate density group is somewhat more efficient, showing the longest residence time and highest cell retention rate around the footprint during the repair stage. Furthermore, quantitative kinetic investigation demonstrates that labeled MSCs are cleared by feces and urine. Histomorphometric analysis demonstrates that the moderate density group achieves maximum therapeutic effect and labeled MSCs do not induce any injury or inflammation to major organs, which suggests that administration of too many or few MSCs may decrease their effectiveness. Such an imaging approach provides spatiotemporal evidence for response to MSC therapy in vivo, facilitating the optimization of MSC therapy.

Modulating the distribution and fate of exogenously delivered MSCs to enhance therapeutic potential: knowns and unknowns

Mesenchymal stem/stromal cells (MSCs) are undergoing intensive translational research for several debilitating conditions, including critical illnesses such as ARDS and sepsis. MSCs exert diverse biologic effects via their interaction with host tissues, via mechanisms that require the MSC to be in close proximity to the area of injury. Fully harnessing the therapeutic potential of advanced medicinal therapeutic products such as MSCs and their successful translation to clinical use requires a detailed understanding of MSC distribution and persistence in the injured tissues.

Key aspects include understanding MSC distribution within the body, the response of the host to MSC administration, and the ultimate fate of exogenously administered MSCs within the host. Factors affecting this interaction include the MSC tissue source, the in vitro MSC culture conditions, the route of MSC administration and the specific issues relating to the target disease state, each of which remains to be fully characterised. Understanding these factors may generate strategies to modify MSC distribution and fate that may enhance their therapeutic effect.

This review will examine our understanding of the mechanisms of action of MSCs, the early and late phase distribution kinetics of MSCs following in vivo administration, the ultimate fate of MSCs following administration and the potential importance of these MSC properties to their therapeutic effects. We will critique current cellular imaging and tracking methodologies used to track exogenous MSCs and their suitability for use in patients, discuss the insights they provide into the distribution and fate of MSCs after administration, and suggest strategies by which MSC biodistribution and fate may be modulated for therapeutic effect and clinical use.

In conclusion, a better understanding of patterns of biodistribution and of the fate of MSCs will add important additional safety data regarding MSCs, address regulatory requirements, and may uncover strategies to increase the distribution and/or persistence of MSC at the sites of injury, potentially increasing their therapeutic potential for multiple disorders.

Strategies to enhance efficacy of SPION-labeled stem cell homing by magnetic attraction: a systemic review with meta-analysis

Stem cells possess a promising potential in the clinical field. The application and effective delivery of stem cells to the desired target organ or site of injury plays an important role. This review describes strategies on understanding the effective delivery of stem cells labeled with superparamagnetic iron oxide nanoparticles (SPION) using an external magnet to enhance stem cell migration in vivo and in vitro. Fourteen total publications among 174 articles were selected. Stem cell type, SPION characteristics, labeling time, and magnetic force in vivo are considered important factors affecting the effective delivery of stem cells to the homing site. Most papers reported that the efficiency was increased when magnet is applied compared to those without. Ten studies analyzed the homing competency of SPION-labeled MSCs in vitro by observing the migration of the cell toward the external magnet. In cell-based experiments, the mechanism of magnetic attraction, the kind of nanoparticles, and various stem cells were studied well. Meta-analysis has shown the mean size of nanoparticles and degree of recovery or regeneration of damaged target organs upon in vivo studies. This strategy may provide a guideline for designing studies involving stem cell homing and further expand stem cell.

Mesenchymal Stromal Cell Homing: Mechanisms and Strategies for Improvement

Mesenchymal stromal cells (MSCs) have been widely investigated for their therapeutic potential in regenerative medicine, owing to their ability to home damaged tissue and serve as a reservoir of growth factors and regenerative molecules. As such, clinical applications of MSCs are reliant on these cells successfully migrating to the desired tissue following their administration. Unfortunately, MSC homing is inefficient, with only a small percentage of cells reaching the target tissue following systemic administration. This attrition represents a major bottleneck in realizing the full therapeutic potential of MSC-based therapies. Accordingly, a variety of strategies have been employed in the hope of improving this process. Here, we review the molecular mechanisms underlying MSC homing, based on a multistep model involving (1) initial tethering by selectins, (2) activation by cytokines, (3) arrest by integrins, (4) diapedesis or transmigration using matrix remodelers, and (5) extravascular migration toward chemokine gradients. We then review the various strategies that have been investigated for improving MSC homing, including genetic modification, cell surface engineering, in vitro priming of MSCs, and in particular, ultrasound techniques, which have recently gained significant interest. Contextualizing these strategies within the multistep homing model emphasizes that our ability to optimize this process hinges on our understanding of its molecular mechanisms. Moving forward, it is only with a combined effort of basic biology and translational work that the potential of MSC-based therapies can be realized.

The Pros and Cons of Mesenchymal Stem Cell-Based Therapies

The need to search for new, alternative treatments for various diseases has prompted scientists and physicians to focus their attention on regenerative medicine and broadly understood cell therapies. Currently, stem cells are being investigated for their potentially widespread use in therapies for many untreatable diseases. Nowadays modern treatment strategies willingly use mesenchymal stem cells (MSCs) derived from different sources. Researchers are increasingly aware of the nature of MSCs and new possibilities for their use. Due to their properties, especially their ability to self-regenerate, differentiate into several cell lineages and participate in immunomodulation, MSCs have become a promising tool in developing modern and efficient future treatment strategies. The great potential and availability of MSCs allow for their various clinical applications in the treatment of many incurable diseases. In addition to their many advantages and benefits, there are still questions about the use of MSCs. What are the mechanisms of action of MSCs? How do they reach their destination? Is the clinical use of MSCs safe? These are the main questions that arise regarding MSCs when they are considered as therapeutic tools. The diversity of MSCs, their different clinical applications, and their many traits that have not yet been thoroughly investigated are sources of discussions and controversial opinions about these cells. Here, we reviewed the current knowledge about MSCs in terms of their therapeutic potential, clinical effects and safety in clinical applications.

Click Chemistry as a Tool for Cell Engineering and Drug Delivery

Click chemistry has great potential for use in binding between nucleic acids, lipids, proteins, and other molecules, and has been used in many research fields because of its beneficial characteristics, including high yield, high specificity, and simplicity. The recent development of copper-free and less cytotoxic click chemistry reactions has allowed for the application of click chemistry to the field of medicine. Moreover, metabolic glycoengineering allows for the direct modification of living cells with substrates for click chemistry either in vitro or in vivo. As such, click chemistry has become a powerful tool for cell transplantation and drug delivery. In this review, we describe some applications of click chemistry for cell engineering in cell transplantation and for drug delivery in the diagnosis and treatment of diseases.

Cytokines in adipose-derived mesenchymal stem cells promote the healing of liver disease

Adipose-derived mesenchymal stem cells (ADSCs) are a treatment cell source for patients with chronic liver injury. ADSCs are characterized by being harvested from the patient's own subcutaneous adipose tissue, a high cell yield (i.e., reduced immune rejection response), accumulation at a disease nidus, suppression of excessive immune response, production of various growth factors and cytokines, angiogenic effects, anti-apoptotic effects, and control of immune cells via cell-cell interaction. We previously showed that conditioned medium of ADSCs promoted hepatocyte proliferation and improved the liver function in a mouse model of acute liver failure. Furthermore, as found by many other groups, the administration of ADSCs improved liver tissue fibrosis in a mouse model of liver cirrhosis. A comprehensive protein expression analysis by liquid chromatography with tandem mass spectrometry showed that the various cytokines and chemokines produced by ADSCs promote the healing of liver disease. In this review, we examine the ability of expressed protein components of ADSCs to promote healing in cell therapy for liver disease. Previous studies demonstrated that ADSCs are a treatment cell source for patients with chronic liver injury. This review describes the various cytokines and chemokines produced by ADSCs that promote the healing of liver disease.

Functionally Improved Mesenchymal Stem Cells to Better Treat Myocardial Infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. Mesenchymal stem cell (MSC) transplantation is considered a promising approach and has made significant progress in preclinical studies and clinical trials for treating MI. However, hurdles including poor survival, retention, homing, and differentiation capacity largely limit the therapeutic effect of transplanted MSCs. Many strategies such as preconditioning, genetic modification, cotransplantation with bioactive factors, and tissue engineering were developed to improve the survival and function of MSCs. On the other hand, optimizing the hostile transplantation microenvironment of the host myocardium is also of importance. Here, we review the modifications of MSCs as well as the host myocardium to improve the efficacy of MSC-based therapy against MI.

The Dynamic Roles of Mesenchymal Stem Cells in Colon Cancer

Colon cancer is still one of the most common causes of cancer in human and is characterized by lymphocyte infiltrates and originates from the epithelial cells found in the lining of colon or rectum of the gastrointestinal tract. Mesenchymal stem cells (MSCs) are composed of the multipotent stem cell group of stroma and can be differentiated as various cell lineages, such as fibroblasts, osteoblasts, and adipocytes. MSCs provide mechanical and structural support and have potential functions during tumor growth and metastasis. The efficacy of MSC-based therapies is partly dependent on the migration and homing of MSCs to tumors and metastatic sites. However, their migratory and engraftment potential is poorly understood. In this review, the characteristics and mechanisms of MSC's dynamic interaction with colon cancer were summarized, particularly the potential functions of MSCs on colon cancer, including its role in improving tumor growth and as a potential candidate for tumor therapy. Understanding MSC homing provides new insights into the manipulation of MSC and the improvement of their efficacy for colon cancer therapy.

Engineering molecular imaging strategies for regenerative medicine

The reshaping of the world's aging population has created an urgent need for therapies for chronic diseases. Regenerative medicine offers a ray of hope, and its complex solutions include material, cellular, or tissue systems. We review basics of regenerative medicine/stem cells and describe how the field of molecular imaging, which is based on quantitative, noninvasive, imaging of biological events in living subjects, can be applied to regenerative medicine in order to interrogate tissues in innovative, informative, and personalized ways. We consider aspects of regenerative medicine for which molecular imaging will benefit. Next, genetic and nanoparticle-based cell imaging strategies are discussed in detail, with modalities like magnetic resonance imaging, optical imaging (near infra-red, bioluminescence), raman microscopy, and photoacoustic microscopy), ultrasound, computed tomography, single-photon computed tomography, and positron emission tomography. We conclude with a discussion of "next generation" molecular imaging strategies, including imaging host tissues prior to cell/tissue transplantation.

Recent Advances in Tracking the Transplanted Stem Cells Using Near-Infrared Fluorescent Nanoprobes: Turning from the First to the Second Near-Infrared Window

Stem cell-based regenerative medicine has attracted tremendous attention for its great potential to treat numerous incurable diseases. Tracking and understanding the fate and regenerative capabilities of transplanted stem cells is vital for improving the safety and therapeutic efficacy of stem cell-based therapy, therefore accelerating the clinical application of stem cells. Fluorescent nanoparticles (NPs) have been widely used for in vivo tracking of the transplanted stem cells. Among these fluorescent NPs, near-infrared (NIR) NPs have greatly improved the sensitivity, tissue penetration depth, spatial and temporal resolutions of the fluorescence imaging-based stem cell tracking technologies due to the reduced absorption, scattering, and autofluorescence of NIR fluorescence in tissues. Here, this review summarizes the recent studies regarding the tracking of transplanted stem cells using NIR NPs and emphasizes the recent advances of fluorescence imaging in the second NIR window (NIR-II, 1000-1700 nm). Furthermore, the challenges and future prospects of the NIR NP-based technologies are also discussed.

Potential Therapeutic Strategy in Chronic Obstructive Pulmonary Disease Using Pioglitazone-Augmented Wharton's Jelly-Derived Mesenchymal Stem Cells

Background

A recent study reported that mesenchymal stem cells possess potential cellular therapeutic properties for treating patients with chronic obstructive pulmonary disease, which is characterized by emphysema. We examined the potential therapeutic effect of Wharton's Jelly-derived mesenchymal stem cells (WJMSCs), following pretreatment with pioglitazone, in lung regeneration mouse emphysema models.

Methods

We used two mouse emphysema models, an elastase-induced model and a cigarette smoke-induced model. We intravenously injected WJMSCs (1×10⁴/mouse) to mice, pretreated or not, with pioglitazone for 7 days. We measured the emphysema severity by mean linear intercepts (MLI) analysis using lung histology.

Results

Pioglitazone pretreated WJMSCs (pioWJMSCs) were associated with greater lung regeneration than non-augmented WJMSCs in the two mouse emphysema models. In the elastase-induced emphysema model, the MLIs were 59.02±2.42 µm (n=6), 72.80±2.87 µm (n=6), for pioWJMSCs injected mice, and non-augmented WJMSCs injected mice, respectively (p<0.01). Both pioWJMSCs and non-augmented WJMSCs showed regenerative effects in the cigarette smoke emphysema model (MLIs were 41.25±0.98 [n=6] for WJMSCs and38.97±0.61 µm [n=6] for pioWJMSCs) compared to smoking control mice (51.65±1.36 µm, n=6). The mean improvement of MLI appeared numerically better in pioWJMSCs than in non-augmented WJMSCs injected mice, but the difference did not reach the level of statistical significance (p=0.071).

Conclusion

PioWJMSCs may produce greater lung regeneration, compared to non-augmented WJMSCs, in a mouse emphysema model.