The Effect of Plasma Rich in Growth Factors on Microglial Migration, Macroglial Gliosis and Proliferation, and Neuronal Survival

The molecular mechanism of human stem cell-derived extracellular vesicles in retinal repair and regeneration

Extracellular vesicles (EVs), including microvesicles (MVs) and exosomes, play a critical role in metabolic regulation and intracellular communication. Stem cell-derived EVs are considered to have the potential for regeneration, like stem cells, while simultaneously avoiding the risk of immune rejection or tumour formation. The therapeutic effect of stem cell-derived EVs has been proven in many diseases. However, the molecular mechanism of stem cell-derived EVs in retinal repair and regeneration has not been fully clarified. In this review, we described the biological characteristics of stem cell-derived EVs, summarized the current research on stem cell-derived EV treatment in retinal repair and regeneration, and discussed the potential and challenges of stem cell-derived EVs in translational medicine.

Effectiveness of Platelet-Rich Plasma for Patients With Carpal Tunnel Syndrome: A Systematic Review and meta-Analysis of Current Evidence in Randomized Controlled Trials

Background: Recently, there was a series of clinical studies focusing on local injection of platelet-rich plasma (PRP) for treatment of patients with carpal tunnel syndrome (CTS). However, the safety and efficacy of PRP in these CTS patients remains controversial. Therefore, we performed a systematic review to compare PRP with other conservative treatments in treatment of CTS patients.

Methods: We systematically searched from electronic databases (Cochrane, PubMed, Web of Science, and EMBASE) up to 10 December 2021. The data of clinical results were extracted and analyzed by RevMan Manager 5.4.

Results: Finally, eight randomized controlled studies, involving 220 CTS patients undergoing local injection of PRP were enrolled in this systematic review. All enrolled trials were considered to be of high quality. In the short-term efficacy, the PRP group was significantly lower in symptom severity scale (SSS) compared with the control group (MD = −2.00; 95% CI, −3.15 to −0.85; p = 0.0007; I² = 0%). In the mid-term efficacy, the PRP group was significantly effective than the control group in the visual analogue scale (MD = −0.63; 95% CI, −1.22 to −0.04; p = 0.04; I² = 61%), SSS (MD = −3.56; 95% CI, −4.93 to −2.18; p < 0.00001; I² = 0%), functional status scale (MD = −2.29; 95% CI, −3.03 to −1.56; p < 0.00001; I² = 45%), sensory peak latency (MD = −0.39; 95% CI, −0.58 to −0.19; p = 0.0001; I² = 0%) and cross-sectional area of median nerve (MD = -0.20; 95% CI, −0.31 to −0.10; p = 0.0002; I² = 0%). In the mid-long-term efficacy, the PRP group was only significantly lower in SSS compared with the control group (MD = −2.71; 95% CI, −4.33 to −1.10; p = 0.001; I² = 38%).

Conclusion: Local PRP injection is more effective than other conservative treatments in terms of mid-term efficacy in relieving pain, improving wrist function and symptoms, reducing MN swelling, and partially improving electrophysiological indicators. However, the long-term adverse side and consensus on standardization of PRP in CTS patients still need further large-scale trials.

Plasma Rich in Growth Factors (PRGF) Increases the Number of Retinal Müller Glia in Culture but Not the Survival of Retinal Neurons

Plasma rich in growth factors (PRGF) is a subtype of platelet-rich plasma (PRP) that stimulates tissue regeneration and may promote neuronal survival. It has been employed in ophthalmology to achieve tissue repair in some retinal pathologies, although how PRGF acts in the retina is still poorly understood. As a part of the central nervous system, the retina has limited capacity for repair capacity following damage, and retinal insult can provoke the death of retinal ganglion cells (RGCs), potentially producing irreversible blindness. RGCs are in close contact with glial cells, such as Müller cells, that help maintain homeostasis in the retina. In this study, the aim was to determine whether PRGF can protect RGCs and whether it increases the number of Müller cells. Therefore, PRGF were tested on primary cell cultures of porcine RGCs and Müller cells, as well as on co-cultures of these two cell types. Moreover, the inflammatory component of PRGF was analyzed and the cytokines in the different PRGFs were quantified. In addition, we set out to determine if blocking the inflammatory components of PRGF alters its effect on the cells in culture. The presence of PRGF compromises RGC survival in pure cultures and in co-culture with Müller cells, but this effect was reversed by heat-inactivation of the PRGF. The detrimental effect of PRGF on RGCs could be in part due to the presence of cytokines and specifically, to the presence of pro-inflammatory cytokines that compromise their survival. However, other factors are likely to be present in the PRGF that have a deleterious effect on the RGCs since the exposure to antibodies against these cytokines were insufficient to protect RGCs. Moreover, PRGF promotes Müller cell survival. In conclusion, PRGF hinders the survival of RGCs in the presence or absence of Müller cells, yet it promotes Müller cell survival that could be the reason of retina healing observed in the in vivo treatments, with some cytokines possibly implicated. Although PRGF could stimulate tissue regeneration, further studies should be performed to evaluate the effect of PRGF on neurons and the implication of its potential inflammatory role in such processes.