Intrasplenic transplantation of bioencapsulated mesenchymal stem cells improves the recovery rates of 90% partial hepatectomized rats

Cell microencapsulation technologies for sustained drug delivery: Latest advances in efficacy and biosafety

The development of cell microencapsulation systems began several decades ago. However, today few systems have been tested in clinical trials. For this reason, in the last years, researchers have directed efforts towards trying to solve some of the key aspects that still limit efficacy and biosafety, the two major criteria that must be satisfied to reach the clinical practice. Regarding the efficacy, which is closely related to biocompatibility, substantial improvements have been made, such as the purification or chemical modification of the alginates that normally form the microspheres. Each of the components that make up the microcapsules has been carefully selected to avoid toxicities that can damage the encapsulated cells or generate an immune response leading to pericapsular fibrosis. As for the biosafety, researchers have developed biological circuits capable of actively responding to the needs of the patients to precisely and accurately release the demanded drug dose. Furthermore, the structure of the devices has been subject of study to adequately protect the encapsulated cells and prevent their spread in the body. The objective of this review is to describe the latest advances made by scientist to improve the efficacy and biosafety of cell microencapsulation systems for sustained drug delivery, also highlighting those points that still need to be optimized.

Increased Mesenchymal Stem Cell Functionalization in Three-Dimensional Manufacturing Settings for Enhanced Therapeutic Applications

Mesenchymal stem/stromal cell (MSC) exist within their in vivo niches as part of heterogeneous cell populations, exhibiting variable stemness potential and supportive functionalities. Conventional extensive 2D in vitro MSC expansion, aimed at obtaining clinically relevant therapeutic cell numbers, results in detrimental effects on both cellular characteristics (e.g., phenotypic changes and senescence) and functions (e.g., differentiation capacity and immunomodulatory effects). These deleterious effects, added to the inherent inter-donor variability, negatively affect the standardization and reproducibility of MSC therapeutic potential. The resulting manufacturing challenges that drive the qualitative variability of MSC-based products is evident in various clinical trials where MSC therapeutic efficacy is moderate or, in some cases, totally insufficient. To circumvent these limitations, various in vitro/ex vivo techniques have been applied to manufacturing protocols to induce specific features, attributes, and functions in expanding cells. Exposure to inflammatory cues (cell priming) is one of them, however, with untoward effects such as transient expression of HLA-DR preventing allogeneic therapeutic schemes. MSC functionalization can be also achieved by in vitro 3D culturing techniques, in an effort to more closely recapitulate the in vivo MSC niche. The resulting spheroid structures provide spatial cell organization with increased cell–cell interactions, stable, or even enhanced phenotypic profiles, and increased trophic and immunomodulatory functionalities. In that context, MSC 3D spheroids have shown enhanced “medicinal signaling” activities and increased homing and survival capacities upon transplantation in vivo. Importantly, MSC spheroids have been applied in various preclinical animal models including wound healing, bone and osteochondral defects, and cardiovascular diseases showing safety and efficacy in vivo. Therefore, the incorporation of 3D MSC culturing approach into cell-based therapy would significantly impact the field, as more reproducible clinical outcomes may be achieved without requiring ex vivo stimulatory regimes. In the present review, we discuss the MSC functionalization in 3D settings and how this strategy can contribute to an improved MSC-based product for safer and more effective therapeutic applications.

Cellular Spheroids of Mesenchymal Stem Cells and Their Perspectives in Future Healthcare

Intrinsic cellular properties of several types of cells are dramatically altered as the culture condition shifts from two-dimensional (2D) to three-dimensional (3D) environment. Currently, several lines of evidence have demonstrated the therapeutic potential of mesenchymal stem cells (MSCs) in regenerative medicine. MSCs not only replenish the lost cells, they also promote the regeneration of impaired tissues by modulating the immune responses. Following the development of 3D cell culture, the enhanced therapeutic efficacy of spheroid-forming MSCs have been identified in several animal disease models by promoting differentiation or trophic factor secretion, as compared to planar-cultured MSCs. Due to the complicated and multifunctional applications in the medical field, MSCs are recently named as medicinal signaling cells. In this review, we summarize the predominant differences of cell–environment interactions for the MSC spheroids formed by chitosan-based substrates and other scaffold-free approaches. Furthermore, several important physical and chemical factors affecting cell behaviors in the cell spheroids are discussed. Currently, the understanding of MSCs spheroid interactions is continuously expanding. Overall, this article aims to review the broad advantages and perspectives of MSC spheroids in regenerative medicine and in future healthcare.

Multipotent stromal cells stimulate liver regeneration by influencing the macrophage polarization in rat

AIM

To investigate the influence of the umbilical cord-derived multipotent stromal cells (MSCs) on recovery of the liver after the subtotal resection, that is, removal of 80% of the organ mass, a renowned model of the small-for-size liver remnant syndrome.

METHODS

The MSCs were obtained from the intervascular tissue of umbilical cords, dissected from rat fetuses, by the explant culture technique. The vital labeling of MSCs with РКН26 was carried out on the 3rd passage. The subtotal resection was performed on male Sprague-Dawley rats. The experimental group animals received a transplant 10⁶ MSCs infused into the spleen. Hepatocyte proliferation was assessed by counting of either mitotic figures or Ki67-positive cells in microscopic images. MSC differentiation was assessed with antibodies to hepatocyte-specific marker cytokeratin 18 (CK18), cholangiocyte-specific protein CK19, smooth muscle cell-specific protein α-SMA, the endothelial cell marker CD31, or the active fibroblast marker FAPα. Total macrophages of the liver were selectively stained in cryosections incubated with anti-CD68 antibodies (1:100, Abcam), while the M2a and M2c macrophage populations were selectively stained with anti-CD206 antibodies. Expression of interleukin and growth factor genes was evaluated with PCR-RT.

RESULTS

Intrasplenic allogeneic transplantation of the umbilical cord-derived multipotent stromal cells stimulates reparative processes within the residual liver tissue after subtotal resection (removal of 80% of the organ mass), as indicated by increased rates of hepatocyte proliferation and accelerated organ mass recovery. These effects may result from paracrine influence of the transplanted cells on the resident macrophage population of the liver. The transplantation favors polarization of macrophages to M2 phenotype (the M2-polarized macrophages specifically express CD206; they are known to suppress inflammation and support tissue repair). No differentiation of the transplanted cells into any of the liver cell types have been observed in the study.

CONCLUSION

We found no direct evidence for the paracrine effect of MSCs on liver regeneration after the subtotal liver resection in rats. However, the paracrine mechanism of the therapeutic activity of transplanted MSC is indirectly indicated by a decrease in the total number of CD68 + macrophages and an increase in the proportion of M2 pro-repair macrophages in the regenerating liver as compared to animals in which the transplantation was only mimicked.

Effect of mesenchymal stem cells on small intestinal injury in a rat model of acute necrotizing pancreatitis

BACKGROUND

Acute necrotizing pancreatitis (ANP) is often complicated by multiple organ failure. The small intestine is frequently damaged during ANP. Capillary leakage in multiple organs during ANP is one of the most important causes of multiple organ dysfunction. Damage to the capillary endothelial barrier and impaired water transportation could lead to capillary leakage in ANP.

METHODS

Sprague-Dawley (SD) rats were randomized into a control group, the ANP group, the culture media-treated group, or the bone marrow-derived mesenchymal stem cell (BMSC)-treated group (30 rats in each group). Ten rats in each group were sacrificed at 6, 12, and 24 h after induction of experimental models. Serum, ascites, pancreatic, and small intestinal samples were collected. The levels of serum and ascites albumin and amylases were measured, pancreatic histology was assessed, and the connection changes between vessel endothelial cells were evaluated using scanning electron microscopy (SEM). Capillary leakage in small intestinal tissue was observed visually by tracking fluorescein isothiocyanate (FITC)-albumin, and was measured by the Evans blue extravasation method. The location and expression of aquaporin 1 (AQP1) in the small intestine was analyzed using immunohistochemistry, real-time polymerase chain reaction (PCR), and Western blot.

RESULTS

The outcomes showed that the level of serum and ascites amylase is elevated. Conversely, the level of serum albumin is decreased while ascites albumin is elevated. There is damage to pancreatic tissue, and the small intestinal capillary endothelial barrier was aggravated. Furthermore, the expression of AQP1 was reduced significantly after induced ANP. Following treatment with MSCs, the elevation of amylase and the decrease of serum albumin were inhibited, the damage to pancreatic tissue and the level of small intestinal capillary leakage was alleviated, and the downregulation of AQP1 was reversed.

CONCLUSIONS

In conclusion, MSC therapy could alleviate small intestinal injury in rats with ANP, the mechanism of which might be related to reduction of damage to the small intestinal capillary endothelial barrier, and increased expression of AQP1 in the small intestine.

The Protective Effect of Transplanting Liver Cells Into the Mesentery on the Rescue of Acute Liver Failure After Massive Hepatectomy

Postoperative liver failure is one of the most critical complications following extensive hepatectomy. Although transplantation of allogeneic hepatocytes is an attractive therapy for posthepatectomy liver failure, transplanting cells via the portal veins typically causes portal vein embolization. The embolization by transplanted cells would be lethal in patients who have undergone massive hepatectomy. Thus, transplant surgeons need to select extrahepatic sites as transplant sites to prevent portal vein embolization. We aimed to investigate the mechanism of how liver cells transplanted into the mesentery protect recipient rats from acute liver failure after massive hepatectomy. We induced posthepatectomy liver failure by 90% hepatectomy in rats. Liver cells harvested from rat livers were transplanted into the mesenteries of hepatectomized rats. Twenty percent of the harvested cells, which consisted of hepatocytes and nonparenchymal cells, were transplanted into each recipient. The survival rate improved significantly in the liver cell transplantation group compared to the control group 7 days after hepatectomy (69 vs. 7%). Histological findings of the transplantation site, in vivo imaging system study findings, quantitative polymerase chain reaction assays of the transplanted cells, and serum albumin measurements of transplanted Nagase analbuminemic rats showed rapid deterioration of viable transplanted cells. Although viable transplanted cells deteriorated in the transplanted site, histological findings and an adenosine-5'-triphosphate (ATP) assay showed that the transplanted cells had a protective effect on the remaining livers. These results indicated that the paracrine effects of transplanted liver cells had therapeutic effects. The same protective effects were observed in the hepatocyte transplantation group, but not in the liver nonparenchymal cell transplantation group. Therefore, this effect on the remnant liver was mainly due to the hepatocytes among the transplanted liver cells. We demonstrated that transplanted liver cells protect the remnant liver from severe damage after massive hepatectomy.

Elimination of allogeneic multipotent stromal cells by host macrophages in different models of regeneration

Allogeneic multipotent stromal cells were previously thought to be poorly recognized by host immune system; the prolonged survival in host environments was explained by their immune privileged status. As long as the concept is currently reconsidered, the routes of elimination of allogeneic multipotent stromal cells by host immunity must be taken into account. This is necessary for correct comprehension of their therapeutic action. The study was focused upon survival of umbilical cord-derived allogeneic multipotent stromal cells in different rat models of tissue regeneration induced by partial hepatectomy or by critical limb ischemia. The observations were carried out by means of vital labeling of the cells with PKH26 prior to injection, in combination with differential immunostaining of host macrophages with anti-CD68 antibody. According to the results, allogeneic multipotent stromal cells are specifically eliminated by host immune system; the efficacy can reach 100%. Massive clearance of transplanted cells by host macrophages is accompanied by appropriation of the label by the latter, and this is a pronounced case of misleading presentation of exogenous label by host cells. The study emphasizes the role of macrophages in host response and also the need of additional criteria for correct data interpretation.

Therapeutic efficacy and biodistribution of allogeneic mesenchymal stem cells delivered by intrasplenic and intrapancreatic routes in streptozotocin-induced diabetic mice

Introduction

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that have the ability to express and secrete a wide range of immunomodulatory molecules, cytokines, growth factors and antiapoptotic proteins. MSCs modulate both innate and adaptive immune responses making them potential candidates for the treatment of patients with type 1 diabetes mellitus (T1D). However, one problem frequently associated with the systemic MSCs administration is the entrapment of the cells mainly in the lungs. In this sense, trying to avoid the lung barrier, the purpose of this study was to evaluate the long-term therapeutic efficacy and biodistribution of allogeneic adipose tissue-derived MSCs (ADMSCs) injected via two different delivery routes (intrasplenic/I.Sp and intrapancreatic/I.Pc) in a murine model of diabetes induced by streptozotocin (STZ).

Methods

Experimental diabetes was induced in C57BL/6 male mice by multiple low-doses of STZ. MSCs were isolated from adipose tissue (ADMSCs) of Balb/c mice. A single dose of 1x10⁶ ADMSCs was microinjected into the spleen or into the pancreas of diabetic mice. Control group received injection of PBS by I.Sp or I.Pc delivery routes. Glycemia, peripheral glucose response, insulin-producing β cell mass, regulatory T cell population, cytokine profile and cell biodistribution were evaluated after ADMSCs/PBS administration.

Results

ADMSCs injected by both delivery routes were able to decrease blood glucose levels and improve glucose tolerance in diabetic mice. ADMSCs injected by I.Sp route reverted hyperglycemia in 70% of diabetic treated mice, stimulating insulin production by pancreatic β cells. Using the I.Pc delivery route, 42% of ADMSCs-treated mice responded to the therapy. Regulatory T cell population remained unchanged after ADMSCs administration but pancreatic TGF-β levels were increased in ADMSCs/I.Sp-treated mice. ADMSCs administrated by I.Sp route were retained in the spleen and in the liver and ADMSCs injected by I.Pc route remained in the pancreas. However, ADMSCs injected by these delivery routes remained only few days in the recipients.

Conclusion

Considering the potential role of MSCs in the treatment of several disorders, this study reports alternative delivery routes that circumvent cell entrapment into the lungs promoting beneficial therapeutic responses in ADMSCs-treated diabetic mice.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0017-1) contains supplementary material, which is available to authorized users.

Advances in cell encapsulation technology and its application in drug delivery

INTRODUCTION

Cell encapsulation technology has improved enormously since it was proposed 50 years ago. The advantages offered over other alternative systems, such as the prevention of repetitive drug administration, have triggered the use of this technology in multiple therapeutic applications.

AREAS COVERED

In this article, improvements in cell encapsulation technology and strategies to overcome the drawbacks that prevent its use in the clinic have been summarized and discussed. Different studies and clinical trials that have been performed in several therapeutic applications have also been described.

EXPERT OPINION

The authors believe that the future translation of this technology from bench to bedside requires the optimization of diverse aspects: i) biosafety, controlling and monitoring cell viability; ii) biocompatibility, reducing pericapsular fibrotic growth and hypoxia suffered by the graft; iii) control over drug delivery; iv) and the final scale up. On the other hand, an area that deserves more attention is the cryopreservation of encapsulated cells as this will facilitate the arrival of these biosystems to the clinic.

Systemic treatment of acute liver failure with adipose derived stem cells

PURPOSE OF THE STUDY

The definitive treatment for liver failure is, currently, liver transplantation. Research into other possible treatments, focused on achieving regeneration of the liver parenchyma, have led to the development of methods to generate hepatocytes from stem cells. In our study, we transplant allogenic adipose-derived stem cells (ASCs), not previously differentiated to hepatocytes, to treat acute liver failure induced by intraperitoneal administration of carbon tetrachloride (CCl4) in a Sprague-Dawley rat model.

MATERIAL AND METHODS

The ASCs were delivered via the tail vein, having previously been labeled with PKH26, a fluorescent membrane marker. Two control groups were established, Group 1(n = 15) consisting of olive oil (5 mL/kg) and Group 2(n = 15): 1 × 10(6) PKH26-labeled ASCs. Further, two study groups, Group 3(n = 30): CCl4 dissolved in olive oil and Group 4(n = 30): CCl4 dissolved in olive oil and 1 × 10(6) PKH26-labeled ASCs completed the experimental design.

RESULTS

Blood samples were analyzed, finding AST and ALT levels significantly higher in treatment over control groups at 24 and 48 hours. The mortality rates were statistically different between control groups and Group 3 (Group 1-3 p = .04, Group 2-3 p = .04) and between Groups 3 and 4 (p = .02). Examining the liver parenchyma, a significantly higher number of ASCs were observed in Group 4 than in Group 2 at all time points (p = .00).

CONCLUSIONS

The intravenous injection of allogenic ASCs in this model of CCl4-induced liver failure reduced the mortality in treated animals. ASCs injected in the rat tail vein were found in the liver in animals with induced acute liver failure.