The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications

HIF-1α overexpression in mesenchymal stem cell-derived exosome-encapsulated arginine-glycine-aspartate (RGD) hydrogels boost therapeutic efficacy of cardiac repair after myocardial infarction

Aims

Naturally secreted extracellular vesicles (EVs) play important roles in stem-mediated cardioprotection. This study aimed to investigate the cardioprotective function and underlying mechanisms of EVs derived from HIF-1α engineered mesenchymal stem cells (MSCs) in a rat model of AMI.

Methods and results

EVs isolated from HIF-1α engineered MSCs (HIF-1α-EVs) and control MSCs (NC-EVs) were prepared. In in vitro experiments, the EVs were incubated with cardiomyocytes and endothelial cells exposed to hypoxia and serum deprivation (H/SD); in in vivo experiments, the EVs were injected in the acutely infarcted hearts of Sprague-Dawley rats. Compared with NC-EVs, HIF-1α-EVs significantly inhibited the apoptosis of cardiomyocytes and enhanced angiogenesis of endothelial cells; meanwhile, HIF-1α-EVs also significantly shrunk fibrotic area and strengthened cardiac function in infarcted rats. After treatment with EVs/RGD-biotin hydrogels, we observed longer retention, higher stability in HIF-1α-EVs, and stronger cardiac function in the rats. Quantitative real-time PCR (qRT-PCR) displayed that miRNA-221-3p was highly expressed in HIF-1α-EVs. After miR-221-3p was inhibited in HIF-1α-EVs, the biological effects of HIF-1α EVs on apoptosis and angiogenesis were attenuated.

Conclusion

EVs released by MSCs with HIF-1α overexpression can promote the angiogenesis of endothelial cells and the apoptosis of cardiomyocytes via upregulating the expression of miR-221-3p. RGD hydrogels can enhance the therapeutic efficacy of HIF-1α engineered MSCs-derived EVs.

A novel 4D cell culture mimicking stomach peristalsis altered gastric cancer spheroids growth and malignance

In vitrocancer models that can largely mimic thein vivomicroenvironment are crucial for conducting more accurate research. Models of three-dimensional (3D) culture that can mimic some aspects of cancer microenvironment or cancer biopsies that can adequately represent tumor heterogeneity are intensely used currently. Those models still lack the dynamic stress stimuli in gastric carcinoma exposed to stomach peristalsisin vivo. This study leveraged a lab-developed four-dimensional (4D) culture model by a magnetic responsive alginate-based hydrogel to rotating magnets that can mimic stress stimuli in gastric cancer (GC). We used the 4D model to culture human GC cell line AGS and SGC7901, cells at the primary and metastasis stage. We revealed the 4D model altered the cancer cell growth kinetics mechanistically by alteringPCNAandp53expression compared to the 3D culture that lacks stress stimuli. We found the 4D model altered the cancer spheroids stemness as evidenced by enhanced cancer stem cells (CD44) marker expression in AGS spheroids but the expression was dampened in SGC7901 cells. We examined the multi-drug resistance (MDR1) marker expression and found the 4D model dampened the MDR1 expression in SGC7901 cell spheroids, but not in spheroids of AGS cells. Such a model provides the stomach peristalsis mimic and is promising for conducting basic or translational GC-associated research, drug screening, and culturing patient gastric biopsies to tailor the therapeutic strategies in precision medicine.

Mesenchymal stem cells encapsulated into biomimetic hydrogel scaffold gradually release CCL2 chemokine in situ preserving cytoarchitecture and promoting functional recovery in spinal cord injury

Spinal cord injury (SCI) is an acute neurodegenerative disorder caused by traumatic damage of the spinal cord. The neuropathological evolution of the primary trauma involves multifactorial processes that exacerbate the pathology, worsening the neurodegeneration and limiting neuroregeneration. This complexity suggests that multi-therapeutic approaches, rather than any single treatment, might be more effective. Encouraging preclinical results indicate that stem cell-based treatments may improve the disease outcome due to their multi-therapeutic ability. Mesenchymal Stem Cells (MSCs) are currently considered one of the most promising approaches. Significant improvement in the behavioral outcome after MSC treatment sustained by hydrogel has been demonstrated. However, it is still not known how hydrogel contribute to the delivery of factors secreted from MSCs and what factors are released in situ. Among different mediators secreted by MSCs after seeding into hydrogel, we have found CCL2 chemokine, which could account for the neuroprotective mechanisms of these cells. CCL2 secreted from human MSCs is delivered efficaciously in the lesioned spinal cord acting not only on recruitment of macrophages, but driving also their conversion to an M2 neuroprotective phenotype. Surprisingly, human CCL2 delivered also plays a key role in preventing motor neuron degeneration in vitro and after spinal cord trauma in vivo, with a significant improvement of the motor performance of the rodent SCI models.