Extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) have been widely reported as promising cell-free products that show therapeutic effects of the parental cells but not their limitations. Due to the intrinsic liver tropism of MSC-EVs, they have been widely used as therapeutics or drug carriers for treatment of liver diseases. However, rapid clearance from the target site may attenuate the efficiency of systemically administered MSC-EVs. Herein, sustained release into the peritoneum has been proposed as a new strategy to prolong the bioavailability of the MSC-EVs in the target liver. During intraperitoneal injection, clickable polyethylene glycol (PEG) macromeres were mixed with MSC-EVs to form EV-encapsulated PEG hydrogels via a fast, biocompatible click reaction. Upon biodegradation, the EV-laden hydrogels were swollen gradually to release EVs in a sustained manner over 1 month. In vivo tracking of the labeled EVs revealed that the accumulation of EVs in the liver was extended by hydrogel-mediated delivery for 1 month. Four weeks after injection in a rat model of chronic liver fibrosis, the physical and histopathological investigations of the harvested liver showed superior antifibrosis, anti-apoptosis, and regenerative effects of the EVs when delivered by the sustained systemic release (Gel-EV) to the conventional bolus injection (Free-EV). Specifically, the Gel-EV system improved the antifibrosis, anti-inflammation, anti-apoptosis, and regenerative effects of the EVs to nearly 40, 50, 40, and 50% compared to Free-EV, respectively, as was specified by quantification of the fibrotic area, α-SMA density, and caspase-3 density in the harvested tissues and ALT enzyme in serum. This study may potentiate the use of MSC-EVs as cell-free therapeutics for chronic liver failure. The sustained systemic delivery strategy may open a new paradigm to extend the effects of disease-targeting EVs over time.

Various somatic tissue-derived mesenchymal stromal cells (MSCs) have been considered as an attractive therapeutic tool for treatment of liver diseases in which the secretion of soluble factors or extracellular vesicles (EVs) is the most probable mechanism. The experimental application of human embryonic stem cell-derived MSC (ES-MSC) increased rapidly and showed promising results, in vitro and in vivo. However, possible therapeutic effects of human ES-MSC and their EVs on Thioacetamide (TAA)-induced chronic liver injury have not been evaluated yet. Our data indicated that human ES-MSC can significantly suppress the proliferation of peripheral blood mononuclear cells compared to bone marrow (BM)-MSC and adipose (AD)-MSC. Moreover, ES-MSC increased the secretion of anti-inflammatory cytokines (i.e., TGF-β and IL-10) and decreased IFN-γ, compared to other MSCs. ES-MSC EVs demonstrated immunomodulatory activities comparable to parental cells and ameliorated cirrhosis in TAA-induced chronic rat liver injury, that is, reduction in fibrosis and collagen density, necrosis, caspase density, portal vein diameter, and transaminitis. The gene expression analyses also showed upregulation in collagenases (MMP9 and MMP13), anti-apoptotic gene (BCL-2) and anti-inflammatory cytokines (TGF-β1 and IL-10) and down-regulation of major contributors to fibrosis (Col1α, αSMA, and TIMP1), pro-apoptotic gene (BAX) and pro-inflammatory cytokines (TNFα and IL-2) following treatment with ES-MSC and ES-MSC-EV. These results demonstrated that human ES-MSC and ES-MSC EV as an off-the-shelf product, that needs further assessment to be suggested as an allogeneic product for therapeutic applications for liver fibrosis.

Natural killer (NK) cell therapy is one of the most promising treatments for Glioblastoma Multiforme (GBM). However, this emerging technology is limited by the availability of sufficient numbers of fully functional cells. Here, we investigated the efficacy of NK cells that were expanded and treated by interleukin-2 (IL-2) and heat shock protein 70 (HSP70), both in vitro and in vivo. Proliferation and cytotoxicity assays were used to assess the functionality of NK cells in vitro, after which treated and naïve NK cells were administrated intracranially and systemically to compare the potential antitumor activities in our in vivo rat GBM models. In vitro assays provided strong evidence of NK cell efficacy against C6 tumor cells. In vivo tracking of NK cells showed efficient homing around and within the tumor site. Furthermore, significant amelioration of the tumor in rats treated with HSP70/Il-2-treated NK cells as compared to those subjected to nontreated NK cells, as confirmed by MRI, proved the efficacy of adoptive NK cell therapy. Moreover, results obtained with systemic injection confirmed migration of activated NK cells over the blood brain barrier and subsequent targeting of GBM tumor cells. Our data suggest that administration of HSP70/Il-2-treated NK cells may be a promising therapeutic approach to be considered in the treatment of GBM.

Glioblastoma multiforme (GBM) is a unique aggressive tumor and mostly develops in the brain, while rarely spreading out of the central nervous system. It is associated with a high mortality rate; despite tremendous efforts having been made for effective therapy, tumor recurrence occurs with high prevalence. To elucidate the mechanisms that lead to new drug discovery, animal models of tumor progression is one of the oldest and most beneficial approaches to not only investigating the aggressive nature of the tumor, but also improving preclinical research. It is also a useful tool for predicting novel therapies' effectiveness as well as side effects. However, there are concerns that must be considered, such as the heterogeneity of tumor, biological properties, pharma dynamic, and anatomic shapes of the models, which have to be similar to humans as much as possible. Although several methods and various species have been used for this approach, the real recapitulation of the human tumor has