Intratympanic injection of MSC-derived small extracellular vesicles protects spiral ganglion neurons from degeneration.

Sensorineural hearing loss is one of the most prevalent sensory deficits. Spiral ganglion neurons (SGNs) exhibit very limited regeneration capacity and their degeneration leads to profound hearing loss. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEV) have been demonstrated to repair tissue damage in various degenerative diseases. However, the effects of MSC-sEV on SGN degeneration remain unclear. In this study, we investigated the efficacy of MSC-sEV for protection against ouabain-induced SGN degeneration. MSC-sEV were derived from rat bone marrow and their components related to neuron growth were determined by proteomic analysis. In primary culture SGNs, MSC-sEV significantly promoted neurite growth and growth cone development. The RNA-Seq analysis of SGNs showed that enriched pathways include neuron development and axon regeneration, consistent with proteomics. In ouabain induced SGN degeneration rat model, MSC-sEV administration via intratympanic injection significantly enhanced SGN survival and mitigated hearing loss. Furthermore, after ouabain treatment, SGNs displayed evident signs of apoptosis, including nuclei condensation and fragmentation, with numerous cells exhibiting TUNEL-positive. However, administration of MSC-sEV effectively decreased the number of TUNEL-positive cells and reduced caspase-3 activation. In conclusion, our findings demonstrate the potential of MSC-sEV in preventing SGN degeneration and promoting neural growth, suggesting intratympanic injection of MSC-sEV is a specific and efficient strategy for neural hearing loss.

Long-Term Release of Dexamethasone With a Polycaprolactone-Coated Electrode Alleviates Fibrosis in Cochlear Implantation.

Cochlear implantation (CI) is the major treatment for severe sensorineural hearing loss. However, the fibrotic tissue forming around the electrodes reduces the treatment effectiveness of CI. Dexamethasone (DEX) is usually applied routinely in perioperative treatment of cochlear implantation (CI), but its diffusion in the inner ear after systemic administration is limited. In the present study, an electrode coated with polycaprolactone (PCL) loaded with dexamethasone was developed with a simple preparation process to maintain the stability of the electrode itself. The DEX-loaded PCL coating has good biocompatibility and does not change the smoothness, flexibility, or compliance of the implant electrode. Stable and effective DEX concentrations were maintained for more than 9 months. Compared with the pristine electrode, decreasing intracochlear fibrosis, protection of hair cells and spiral ganglion cells, and better residual hearing were observed 5 weeks after PCL-DEX electrode implantation. The PCL-DEX electrode has great potential in preventing hearing loss and fibrosis by regulating macrophages and inhibiting the expression of the fibrosis-related factors IL-1ß, TNF-α, IL-4, and TGF-ß1. In conclusion, the PCL-DEX electrode coating shows promising application in CI surgery.

Preparation, characterization, and in vitro/vivo evaluation of dexamethasone/poly(ε-caprolactone)-based electrode coatings for cochlear implants.

With dexamethasone as the model drug and polycaprolactone (PCL) as the carrier material, a drug delivery coating for cochlear electrodes was prepared, to control cochlear fibrosis caused by cochlear implantation. A dexamethasone/poly (ε-caprolactone)-based electrode coating was prepared using the impregnation coating method. Preparation parameters were optimized, yielding 1 impregnation instance, impregnation time of 10 s, and PCL concentration of 10%. The coating was characterized in vitro using scanning electron microscopy, a universal machine, high-performance liquid chromatography, and CCK-8. The surface was porous and uniformly thick (average thickness, 48.67 µm)-with good flexibility, long-term slow drug release, and optimal drug concentration-and was biologically safe. The experimental results show that PCL is an ideal controlled-release material for dexamethasone as a drug carrier coating for cochlear implants.

Experimental study for the establishment of a chemotherapy-induced ovarian insufficiency model in rats by using cyclophosphamide combined with busulfan.

With an improvement in the survival rate of cancer patients, chemotherapy-induced premature ovarian insufficiency (POI) is increasingly affecting the quality of life of female patients. Currently, there are many relevant studies using mice as an animal model. However, a large coefficient of variation for weight in mice is not appropriate for endocrine-related studies, compared with rats; therefore, it is necessary to identify an appropriate experimental model in rats. In this study, cyclophosphamide combined with busulfan was used to establish an animal model. We compared several common modeling methods using chemotherapeutic drugs, cisplatin, cyclophosphamide, and 4-vinylcyclohexene diepoxide (VCD), and we found that the combination of cyclophosphamide and busulfan was more effective in establishing a POI model in rats with few side effects by analyzing general physical conditions, pathological tissue sections of heart, liver, lung, spleen, kidney, uterus, and ovary, serum hormone levels, and follicle counts; thus, providing a more reliable model basis for subsequent studies.

Effects of Human Amnion-Derived Mesenchymal Stem Cell (hAD-MSC) Transplantation In Situ on Primary Ovarian Insufficiency in SD Rats.

Human amnion-derived mesenchymal stem cell (hAD-MSC) transplantation can repair ovarian injury and improve ovarian function in rats with chemotherapy-induced primary ovarian insufficiency (POI). However, ensuring that stem cells home to the ovary to improve their effects on ovarian injury is challenging. This research aimed to directly inject ovarian tissue with hAD-MSCs and improve the homing of stem cells to the ovary. The animals were divided into POI, hAD-MSC (tail vein) treatment, hAD-MSC (in situ) treatment, and control groups. POI rat models were established by intraperitoneal injection of cyclophosphamide (CTX) and busulfan (BUS). The hAD-MSCs isolated from the amnion were injected into the tail vein or ovary of POI rats. The estrous cycle, serum sex hormone levels, follicle counts, ovarian pathological changes, and proteome of the ovaries were evaluated. hAD-MSCs were successfully isolated and cultured from the amnion. Both hAD-MSC (tail vein) and hAD-MSC (in situ) transplantation increased body weight, improved the AMH levels and follicle numbers, and reduced reproductive organ injuries in POI rats. Transplantation of hAD-MSCs (in situ) upregulated 24 proteins and downregulated 4 proteins. Both hAD-MSC (tail vein) and hAD-MSC (in situ) transplantations can repair ovarian injury and improve ovarian function in rats with chemotherapy-induced POI. The paracrine proteome of hAD-MSCs in the ovarian microenvironment can protect against chemotherapy-induced damage by reducing apoptosis and promoting angiogenesis, cell proliferation, and gene expression.

Human amnion-derived mesenchymal stem cell (hAD-MSC) transplantation improves ovarian function in rats with premature ovarian insufficiency (POI) at least partly through a paracrine mechanism.

BACKGROUND: Chemotherapy can induce premature ovarian insufficiency (POI) and reduce fertility in young female patients. Currently, there is no effective therapy for POI. Human amnion-derived mesenchymal stem cells (hAD-MSCs) may be a promising seed cell for regenerative medicine. This study investigated the effects and mechanisms of hAD-MSC transplantation on chemotherapy-induced POI in rats. METHODS: Chemotherapy-induced POI rat models were established by intraperitoneal injection of cyclophosphamide. Seventy-two female SD rats were randomly divided into control, POI, and hAD-MSC-treated groups. hAD-MSCs were labeled with PKH26 and injected into the tail veins of POI rats. To examine the underlying mechanisms, the differentiation of transplanted hAD-MSCs in the POI ovaries was analyzed by immunofluorescent staining. The in vitro expression of growth factors secreted by hAD-MSCs in hAD-MSC-conditioned media (hAD-MSC-CM) was analyzed by ELISA. Sixty female SD rats were divided into control, POI, and hAD-MSC-CM-treated groups, and hAD-MSC-CM was injected into the bilateral ovaries of POI rats. After hAD-MSC transplantation or hAD-MSC-CM injection, serum sex hormone levels, estrous cycles, ovarian pathological changes, follicle counts, granulosa cell (GC) apoptosis, and Bcl-2, Bax, and VEGF expression in ovaries were examined. RESULTS: PKH26-labeled hAD-MSCs mainly homed to ovaries after transplantation. hAD-MSC transplantation reduced ovarian injury and improved ovarian function in rats with POI. Transplanted hAD-MSCs were only located in the interstitium of ovaries, rather than in follicles, and did not express the typical markers of oocytes and GCs, which are ZP3 and FSHR, respectively. hAD-MSCs secreted FGF2, IGF-1, HGF, and VEGF, and those growth factors were detected in the hAD-MSC-CM. hAD-MSC-CM injection improved the local microenvironment of POI ovaries, leading to a decrease in Bax expression and an increase in Bcl-2 and endogenous VEGF expression in ovarian cells, which inhibited chemotherapy-induced GC apoptosis, promoted angiogenesis and regulated follicular development, thus partly reducing ovarian injury and improving ovarian function in rats with POI. CONCLUSIONS: hAD-MSC transplantation can improve ovarian function in rats with chemotherapy-induced POI at least partly through a paracrine mechanism. The presence of a paracrine mechanism accounting for hAD-MSC-mediated recovery of ovarian function might be attributed to the growth factors secreted by hAD-MSCs.