Protective effects of human umbilical cord mesenchymal stem cells on retinal ganglion cells in mice with acute ocular hypertension

Future directions of glaucoma treatment: emerging gene, neuroprotection, nanomedicine, stem cell, and vascular therapies

PURPOSE OF REVIEW

The aim of this article is to summarize current research on novel gene, stem cell, neuroprotective, nanomedicine, and vascular therapies for glaucoma.

RECENT FINDINGS

Gene therapy using viral vectors and siRNA have been shown to reduce intraocular pressure by altering outflow and production of aqueous humor, to reduce postsurgical fibrosis with few adverse effects, and to increase retinal ganglion cell (RGC) survival in animal studies. Stem cells may treat glaucoma by replacing or stimulating proliferation of trabecular meshwork cells, thus restoring outflow facility. Stem cells can also serve a neuroprotective effect by differentiating into RGCs or preventing RGC loss via secretion of growth factors. Other developing neuroprotective glaucoma treatments which can prevent RGC death include nicotinamide, the NT-501 implant which secretes ciliary neurotrophic factor, and a Fas-L inhibitor which are now being tested in clinical trials. Recent studies on vascular therapy for glaucoma have focused on the ability of Rho Kinase inhibitors and dronabinol to increase ocular blood flow.

SUMMARY

Many novel stem cell, gene, neuroprotective, nanomedicine, and vascular therapies have shown promise in preclinical studies, but further clinical trials are needed to demonstrate safety and efficacy in human glaucomatous eyes. Although likely many years off, future glaucoma therapy may take a multifaceted approach.

Ultrasound Targeted Microbubble Destruction Promotes the Therapeutic Effect of HUMSC Transplantation on Glaucoma-Caused Optic Nerve Injury in Rabbits

Purpose

The purpose of this study was to explore the therapeutic effect of human umbilical cord mesenchymal stem cell (HUMSC) transplantation alone or assisted with ultrasound targeted microbubble destruction (UTMD) on optic neuropathy in a novel and practical model of experimental glaucoma in rabbits.

Methods

Eight New Zealand white healthy rabbits were used as the control group (group A). Twenty-four experimental glaucomatous rabbits were established as described previously and randomly divided into three groups: (1) received no treatment (group B); (2) received intravitreal transplantation of HUMSCs (group C); and (3) received UTMD-assisted intravitreal transplantation of HUMSCs (group D). After 4 weeks of treatment, the distribution of HUMSCs, retinal thickness, layer structure, retinal ganglion cells (RGCs), and their axons were examined.

Results

After 4 weeks of treatment, HUMSCs were successfully scattered under the retina. HUMSC transplantation significantly increased the regeneration of RGCs and their axons, and restored the retinal structure in glaucomatous rabbits. Moreover, the application of UTMD enhances HUMSC distribution and achieved more significant therapeutic effect.

Conclusions

Intravitreal transplantation of HUMSCs effectively repaired glaucomatous optic nerve injury, and UTMD enhanced the successful delivery of HUMSCs into injured retina, promoting its therapeutic effects remarkably.

Translational Relevance

This study demonstrated that HUMSC transplantation repaired the glaucoma-caused nerve injury significantly and the combination of UTMD can augment the therapeutic effect further, which has important clinical guiding significance for the development of therapeutic strategies of glaucoma.

Protective effect of human umbilical cord mesenchymal stem cell-derived exosomes on rat retinal neurons in hyperglycemia through the brain-derived neurotrophic factor/TrkB pathway

AIM

To explore whether human umbilical cord mesenchymal stem cell (hUCMSC)-derived exosomes (hUCMSC-Exos) protect rat retinal neurons in high-glucose (HG) conditions by activating the brain-derived neurotrophic factor (BDNF)-TrkB pathway.

METHODS

hUCMSC-Exos were collected with differential ultracentrifugation methods and observed by transmission electron microscopy. Enzyme-linked immunosorbent assays (ELISAs) was used to quantify BDNF in hUCMSC-Exos, and Western blot was used to identify surface markers of hUCMSC-Exos. Rat retinal neurons were divided into 4 groups. Furthermore, cell viability, cell apoptosis, and TrkB protein expression were measured in retinal neurons.

RESULTS

hUCMSCs and isolated hUCMSC-Exos were successfully cultured. All hUCMSC-Exos showed a diameter of 30 to 150 nm and had a phospholipid bimolecular membrane structure, as observed by transmission electron microscopy. ELISA showed the BDNF concentration of hUCMSCs-Exos was 2483.16±281.75. hUCMSCs-Exos effectively reduced the apoptosis of retinal neuron rate and improved neuron survival rate, meanwhile, the results of immunofluorescence verified the fluorescence intensity of TrKB in neurons increased. And all above effects were reduced by treated hUCMSCs-Exos with BDNF inhibitors. hUCMSC-Exos effectively reduced the apoptosis rate of retinal neurons by activating the BDNF-TrkB pathway in a HG environment.

CONCLUSION

In the HG environment, hUCMSC-Exos could carry BDNF into rat retinal neurons, inhibiting neuronal apoptosis by activating the BDNF-TrkB pathway.