Delivery of Stem Cell Secretome for Therapeutic Applications

Functionalized extracellular nanovesicles as advanced CRISPR delivery systems

The clustered regularly interspaced short palindromic repeat (CRISPR) system, an emerging tool for genome editing, has garnered significant public interest for its potential in treating genetic diseases. Despite the rapid advancements in CRISPR technology, the progress in developing effective delivery strategies lags, impeding its clinical application. Extracellular nanovesicles (EVs), either in their endogenous forms or with engineered modifications, have emerged as a promising solution for CRISPR delivery. These EVs offer several advantages, including high biocompatibility, biological permeability, negligible immunogenicity, and straightforward production. Herein, we first summarize various types of functional EVs for CRISPR delivery, such as unmodified, modified, engineered virus-like particles (VLPs), and exosome-liposome hybrid vesicles, and examine their distinct intracellular pathways. Then, we outline the cutting-edge techniques for functionalizing extracellular vesicles, involving producer cell engineering, vesicle engineering, and virus-like particle engineering, emphasizing the diverse CRISPR delivery capabilities of these nanovesicles. Lastly, we address the current challenges and propose rational design strategies for their clinical translation, offering future perspectives on the development of functionalized EVs.

Smart Microneedle Arrays Integrating Cell-Free Therapy and Nanocatalysis to Treat Liver Fibrosis

Liver fibrosis is a chronic pathological condition lacking specific clinical treatments. Stem cells, with notable potential in regenerative medicine, offer promise in treating liver fibrosis. However, stem cell therapy is hindered by potential immunological rejection, carcinogenesis risk, efficacy variation, and high cost. Stem cell secretome-based cell-free therapy offers potential solutions to address these challenges, but it is limited by low delivery efficiency and rapid clearance. Herein, an innovative approach for in situ implantation of smart microneedle (MN) arrays enabling precisely controlled delivery of multiple therapeutic agents directly into fibrotic liver tissues is developed. By integrating cell-free and platinum-based nanocatalytic combination therapy, the MN arrays can deactivate hepatic stellate cells. Moreover, they promote excessive extracellular matrix degradation by more than 75%, approaching normal levels. Additionally, the smart MN arrays can provide hepatocyte protection while reducing inflammation levels by ≈70-90%. They can also exhibit remarkable capability in scavenging almost 100% of reactive oxygen species and alleviating hypoxia. Ultimately, this treatment strategy can effectively restrain fibrosis progression. The comprehensive in vitro and in vivo experiments, supplemented by proteome and transcriptome analyses, substantiate the effectiveness of the approach in treating liver fibrosis, holding immense promise for clinical applications.

3D Printing of a Vascularized Mini-Liver Based on the Size-Dependent Functional Enhancements of Cell Spheroids for Rescue of Liver Failure

The emerging stem cell-derived hepatocyte-like cells (HLCs) are the alternative cell sources of hepatocytes for treatment of highly lethal acute liver failure (ALF). However, the hostile local environment and the immature cell differentiation may compromise their therapeutic efficacy. To this end, human adipose-derived mesenchymal stromal/stem cells (hASCs) are engineered into different-sized multicellular spheroids and co-cultured with 3D coaxially and hexagonally patterned human umbilical vein endothelial cells (HUVECs) in a liver lobule-like manner to enhance their hepatic differentiation efficiency. It is found that small-sized hASC spheroids, with a diameter of ≈50 µm, show superior pro-angiogenic effects and hepatic differentiation compared to the other counterparts. The size-dependent functional enhancements are mediated by the Wnt signaling pathway. Meanwhile, co-culture of hASCs with HUVECs, at a HUVECs/hASCs seeding density ratio of 2:1, distinctly promotes hepatic differentiation and vascularization both in vitro and in vivo, especially when endothelial cells are patterned into hollow hexagons. After subcutaneous implantation, the mini-liver, consisting of HLC spheroids and 3D-printed interconnected vasculatures, can effectively improve liver regeneration in two ALF animal models through amelioration of local oxidative stress and inflammation, reduction of liver necrosis, as well as increase of cell proliferation, thereby showing great promise for clinical translation.

Rhoa/ROCK, mTOR and Secretome-Based Treatments for Ischemic Stroke: New Perspectives

Ischemic stroke triggers a complex cascade of cellular and molecular events leading to neuronal damage and tissue injury. This review explores the potential therapeutic avenues targeting cellular signaling pathways implicated in stroke pathophysiology. Specifically, it focuses on the articles that highlight the roles of RhoA/ROCK and mTOR signaling pathways in ischemic brain injury and their therapeutic implications. The RhoA/ROCK pathway modulates various cellular processes, including cytoskeletal dynamics and inflammation, while mTOR signaling regulates cell growth, proliferation, and autophagy. Preclinical studies have demonstrated the neuroprotective effects of targeting these pathways in stroke models, offering insights into potential treatment strategies. However, challenges such as off-target effects and the need for tissue-specific targeting remain. Furthermore, emerging evidence suggests the therapeutic potential of MSC secretome in stroke treatment, highlighting the importance of exploring alternative approaches. Future research directions include elucidating the precise mechanisms of action, optimizing treatment protocols, and translating preclinical findings into clinical practice for improved stroke outcomes.

Mesenchymal Stem Cell-Derived Exosomes in Various Chronic Liver Diseases: Hype or Hope?

Chronic liver conditions are associated with high mortality rates and have a large adverse effect on human well-being as well as a significant financial burden. Currently, the only effective treatment available for the effects of liver failure and cirrhosis resulting from the progression of several chronic liver diseases is liver transplantation carried out at the original location. This implies that developing novel and effective treatments is imperative. Regenerative medicine has long been associated with stem cell therapy. Mesenchymal stem cells (MSCs), a type of cell with great differentiation potential, have become the preferred source for stem cell therapy. According to recent studies, MSCs' paracrine products-rather than their capacity for differentiation-play a significant therapeutic effect. MSC exosomes, a type of extracellular vesicle (MSC-EV), came into view as the paracrine substances of MSCs. According to research, MSC exosomes can maintain tissue homeostasis, which is necessary for healthy tissue function. All tissues contain them, and they take part in a variety of biological activities that support cellular activity and tissue regeneration in order to preserve tissue homeostasis. The outcomes support the use of MSCs and the exosomes they produce as a therapeutic option for a range of diseases. This review provides a brief overview of the source of MSC-EVs and outlines their physiological roles and biochemical capabilities. The elucidation of the role of MSC-EVs in the recovery and repair of hepatic tissues, as well as their contribution to maintaining tissue homeostasis, is discussed in relation to different chronic liver diseases. This review aims to provide new insights into the unique roles that MSC-EVs play in the treatment of chronic liver diseases.

Microfluidic Fabrication of MicroRNA-Induced Hepatocyte-Like Cells/Human Umbilical Vein Endothelial Cells-Laden Microgels for Acute Liver Failure Treatment

Acute liver failure (ALF) is a critical life-threatening disease that occurs due to a rapid loss in hepatocyte functions. Hepatocyte transplantation holds great potential for ALF treatment, as it rapidly supports liver biofunctions and enhances liver regeneration. However, hepatocyte transplantation is still limited by renewable and ongoing cell sources. In addition, intravenously injected hepatocytes are primarily trapped in the lungs and have limited efficacy because of the rapid clearance in vivo. Here, we designed a Y-shaped DNA nanostructure to deliver microRNA-122 (Y-miR122), which could induce the hepatic differentiation and maturation of human mesenchymal stem cells. mRNA sequencing analysis revealed that the Y-miR122 promoted important hepatic biofunctions of the induced hepatocyte-like cells including fat and lipid metabolism, drug metabolism, and liver development. To further improve hepatocyte transplantation efficiency and therapeutic effects in ALF treatment, we fabricated protective microgels for the delivery of Y-miR122-induced hepatocyte-like cells based on droplet microfluidic technology. When cocultured with human umbilical vein endothelial cells in microgels, the hepatocyte-like cells exhibited an increase in hepatocyte-associated functions, including albumin secretion and cytochrome P450 activity. Notably, upon transplantation into the ALF mouse model, the multiple cell-laden microgels effectively induced the restoration of liver function and enhanced liver regeneration. Overall, this study presents an efficient approach from the generation of hepatocyte-like cells to hepatocyte transplantation in ALF therapy.

Mesenchymal stem cell secretome ameliorates over-expression of soluble fms-like tyrosine kinase-1 (sFlt-1) and fetal growth restriction (FGR) in animal SLE model

INTRODUCTION

In the near future, stem cell research may lead to several major therapeutic innovations in medical practice. Secretome, a "by-product" of stem cell line cultures, has many advantages. Its easiness of storage, usage, and fast direct effect are some of those to consider. Fetal growth restriction (FGR) remains one of the significant challenges in maternal-fetal and neonatal medicine. Placentation failure is one of the most profound causal and is often related to increasing sFlt-1 in early pregnancy. This study aimed to investigate hUC-MSC secretome in ameliorating sFlt-1 and how to improve outcomes in preventing FGR in an animal model.

MATERIALS AND METHODS

Pristane-induced systemic lupus erythematosus (SLE) in a mouse model was used to represent placentation failure and its consequences. Twenty-one mice were randomized into three groups: (I) normal pregnancy, (II) SLE, and (III) SLE with secretome treatment. Pristane was administered in all Groups four weeks prior mating period. Secretome was derived from human umbilical cord mesenchymal stem cells (hUC-MSC) conditioned medium on the 3rd and 4th passage, around day-21 until day-28 from the start of culturing process. Mesenchymal stem cell was characterized using flow cytometry for CD105+, CD90+, and CD73+ surface antigen markers. Immunohistochemistry anlysis by using Remmele's Immunoreactive Score (IRS) was used to quantify the placental sFlt-1 expression in each group. Birth weight and length were analyzed as the secondary outcome. The number of fetuses obtained was also calculated for pregnancy loss comparison between Groups.

RESULTS

The administration of secretome of hUC-MSC was found to lower the expression of the placental sFlt-1 significantly in the pristane SLE animal model (10.30 ± 1.40 vs. 4.98 ± 2.57; p < 0.001) to a level seen in normal mouse pregnancies in Group I (3.88 ± 0.49; p = 0.159). Secretome also had a significant effect on preventing fetal growth restriction in the pristane SLE mouse model (birth weight: 354.29 ± 80.76 mg vs. 550 ± 64.03 mg; p < 0.001 and birth length: 14.43 ± 1.27 mm vs. 19.00 ± 1.41 mm), comparable to the birth weight and length of the normal pregnancy in Group I (540.29 ± 75.47 mg and 18.14 ± 1.34 mm, p = 0.808 and = 0.719). Secretome administration also showed a potential action to prevent high number of pregnancy loss as the number of fetuses obtained could be similar to those of mice in the normal pregnant Group (7.71 ± 1.11 vs. 7.86 ± 1.06; p = 0.794).

CONCLUSIONS

Administration of secretome lowers sFlt-1 expression in placenta, improves fetal growth, and prevents pregnancy loss in a mouse SLE model.

Conditioned medium of human menstrual blood-derived endometrial stem cells protects against cell inflammation and apoptosis of Npc1KO N2a cells

Niemann-Pick disease type C1 (NPC1) is a hereditary neurodegenerative disorder caused by a mutation in the NPC1 gene. This gene encodes a transmembrane protein found in lysosomes. This disease characterized by hepatosplenomegaly, neurological impairments and premature death. Recent preclinical studies have shown promising results in using mesenchymal stem cells (MSCs) to alleviate the symptoms of NPC1. One type of MSCs, known as human menstrual blood-derived endometrial stem cells (MenSCs), has attracted attention due to its accessibility, abundant supply, and strong proliferation and regeneration capabilities. However, it remains uncertain whether the conditioned medium of MenSCs (MenSCs-CM) can effectively relieve the symptoms of NPC1. To investigate this further, we employed the CRISPR-Cas9 technique to successfully create a Npc1 gene knockout N2a cell line (Npc1KO N2a). Sanger sequencing confirmed the occurrence of Npc1 gene mutation in these cells, while western blotting revealed a lack of NPC1 protein expression. Filipin staining provided visual evidence of unesterified cholesterol accumulation in Npc1KO N2a cells. Moreover, Npc1KO N2a cells exhibited significantly decreased viability, increased inflammation, and heightened cell apoptosis. Notably, our study demonstrated that the viability of Npc1KO N2a cells was most significantly improved after being cultured by 36 h-collected MenSCs-CM for 0.5 days. Additionally, MenSCs-CM exhibited the ability to effectively reduce inflammation, counteract cell apoptosis, and ameliorate unesterified cholesterol accumulation in Npc1KO N2a cells. This groundbreaking finding establishes, for the first time, the protective effect of MenSCs-CM on N2a cells with Npc1 gene deletion. These findings suggest that the potential of MenSCs-CM as a beneficial therapeutic approach for NPC1 and other neurodegenerative diseases.

Application of stem cells in regeneration medicine

Regeneration is a complex process affected by many elements independent or combined, including inflammation, proliferation, and tissue remodeling. Stem cells is a class of primitive cells with the potentiality of differentiation, regenerate with self-replication, multidirectional differentiation, and immunomodulatory functions. Stem cells and their cytokines not only inextricably linked to the regeneration of ectodermal and skin tissues, but also can be used for the treatment of a variety of chronic wounds. Stem cells can produce exosomes in a paracrine manner. Stem cell exosomes play an important role in tissue regeneration, repair, and accelerated wound healing, the biological properties of which are similar with stem cells, while stem cell exosomes are safer and more effective. Skin and bone tissues are critical organs in the body, which are essential for sustaining life activities. The weak repairing ability leads a pronounced impact on the quality of life of patients, which could be alleviated by stem cell exosomes treatment. However, there are obstacles that stem cells and stem cells exosomes trough skin for improved bioavailability. This paper summarizes the applications and mechanisms of stem cells and stem cells exosomes for skin and bone healing. We also propose new ways of utilizing stem cells and their exosomes through different nanoformulations, liposomes and nanoliposomes, polymer micelles, microspheres, hydrogels, and scaffold microneedles, to improve their use in tissue healing and regeneration.

Microneedles for in situ tissue regeneration

Tissue injury is a common clinical problem, which may cause great burden on patients' life. It is important to develop functional scaffolds to promote tissue repair and regeneration. Due to their unique composition and structure, microneedles have attracted extensive attention in various tissues regeneration, including skin wound, corneal injury, myocardial infarction, endometrial injury, and spinal cord injury et al. Microneedles with micro-needle structure can effectively penetrate the barriers of necrotic tissue or biofilm, therefore improving the bioavailability of drugs. The use of microneedles to deliver bioactive molecules, mesenchymal stem cells, and growth factors in situ allows for targeted tissue and better spatial distribution. At the same time, microneedles can also provide mechanical support or directional traction for tissue, thus accelerating tissue repair. This review summarized the research progress of microneedles for in situ tissue regeneration over the past decade. At the same time, the shortcomings of existing researches, future research direction and clinical application prospect were also discussed.

Next generation of neurological therapeutics: Native and bioengineered extracellular vesicles derived from stem cells

Extracellular vesicles (EVs)-based cell-free therapy, particularly stem cell-derived extracellular vesicles (SC-EVs), offers new insights into treating a series of neurological disorders and becomes a promising candidate for alternative stem cell regenerative therapy. Currently, SC-EVs are considered direct therapeutic agents by themselves and/or dynamic delivery systems as they have a similar regenerative capacity of stem cells to promote neurogenesis and can easily load many functional small molecules to recipient cells in the central nervous system. Meanwhile, as non-living entities, SC-EVs avoid the uncontrollability and manufacturability limitations of live stem cell products in vivo (e.g., low survival rate, immune response, and tumorigenicity) and in vitro (e.g., restricted sources, complex preparation processes, poor quality control, low storage, shipping instability, and ethical controversy) by strict quality control system. Moreover, SC-EVs can be engineered or designed to enhance further overall yield, increase bioactivity, improve targeting, and extend their half-life. Here, this review provides an overview on the biological properties of SC-EVs, and the current progress in the strategies of native or bioengineered SC-EVs for nerve injury repairing is presented. Then we further summarize the challenges of recent research and perspectives for successful clinical application to advance SC-EVs from bench to bedside in neurological diseases.

Cell Secretome Strategies for Controlled Drug Delivery and Wound-Healing Applications

There is significant interest in using stem cells in the management of cutaneous wounds. However, potential safety, efficacy, and cost problems associated with whole-cell transplantation hinder their clinical application. Secretome, a collective of mesenchymal stem-cell-stored paracrine factors, and immunomodulatory cytokines offer therapeutic potential as a cell-free therapy for the treatment of cutaneous wounds. This review explores the possibility of secretome as a treatment for cutaneous wounds and tissue regeneration. The review mainly focuses on in vitro and in vivo investigations that use biomaterials and secretome together to treat wounds, extend secretome retention, and control release to preserve their biological function. The approaches employed for the fabrication of biomaterials with condition media or extracellular vesicles are discussed to identify their future clinical application in wound treatment.