Metabolic activity in cryopreserved and grafted ovarian tissue using high-resolution respirometry

Alpha lipoic acid controls degeneration and ensures follicular development in ovine ovarian tissue cultured in vitro

This study aims to evaluate the effects of adding alpha lipoic acid (ALA) to the in vitro ovarian tissue culture medium, either fresh or after vitrification/warming. For this purpose, 10 ovaries from five adult sheep were used. Each pair of ovaries gave rise to 16 fragments and were randomly distributed into two groups: fresh (n = 8) and vitrified (n = 8). Two fresh fragments were fixed immediately and considered the control, while another six were cultured in vitro for 14 days in the absence; presence of a constant (100 μM/0-14 day) or dynamic (50 μM/day 0-7 and 100 μM/day 8-14) concentration of ALA. As for the vitrified fragments, two were fixed and the other six were cultured in vitro under the same conditions described for the fresh group. All the fragments were subjected to morphological evaluation, follicular development and stromal density (classical histology), DNA fragmentation (TUNEL), senescence (Sudan Black), fibrosis (Masson's Trichome), and endoplasmic reticulum stress (immunofluorescence). Measurements of the antioxidant capacity against the free radicals 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and estradiol (E2) levels in the culture medium was performed. The results showed that in the absence of ALA, in vitro culture of vitrified ovarian fragments showed a significant reduction (P < 0.05) in follicular morphology and increased the presence of senescence and tissue fibrosis (P < 0.05). Dynamic ALA maintained E2 levels unchanged (P > 0.05) until the end of vitrified ovarian tissue culture and controlled the levels of ABTS and DPPH radicals in fresh or vitrified cultures. Therefore, it is concluded that ALA should be added to the vitrified ovarian tissue in vitro culture medium to reduce the damage that leads to loss of ovarian function. To ensure steroidogenesis during in vitro culture, ALA should be added dynamically (different concentrations throughout culture).

Effects of erythropoietin on ischaemia-reperfusion when administered before and after ovarian tissue transplantation in mice

RESEARCH QUESTION

Is the optimal timing for administering erythropoietin to minimize ischaemic injury in ovarian tissue transplantation before ovary removal for cryopreservation and subsequent transplantation or after transplantation?

DESIGN

Thirty Swiss mice (nu/nu) were divided into three groups: treatment control group (n = 10); erythropoietin before harvesting group (EPO-BH) (n = 10) and erythropoietin after transplantation group (EPO-AT) (n = 10). Animals underwent bilateral ovariohysterectomy and their hemiovaries were cryopreserved by slow freezing. At the same time, previously cryopreserved hemiovaries were transplanted subcutaneously in the dorsal region. Erythropoietin (250 IU/kg) and sterile 0.9% saline solution were administered every 12/12 h over 5 consecutive days in the EPO-AT and EPO-BH groups, respectively.

RESULTS

Administration of erythropoietin in the EPO-AT group improved the viability of ovarian follicles, reducing degeneration and increasing the number of morphologically normal growing follicles at 14 days after transplantation compared with the EPO-BH group (P = 0.002). This group also showed higher percentages of proliferative follicles at 7 days after transplantation (P ≤ 0.03), increased blood vessel count (P ≤ 0.03) and greater tissue area occupied by blood vessels at days 7 and 14 after transplantation (P ≤ 0.03), compared with hormone administration before cryopreservation (EPO-BH group) and the treatment control group. Additionally, treatment with erythropoietin before or after transplantation reduced fibrotic areas at 7 days after transplantation (P = 0.004).

CONCLUSION

Erythropoietin treatment after transplantation reduced ischaemic damage in transplanted ovarian tissue, increased angiogenesis, maintenance of ovarian follicle proliferation and reduced fibrosis areas in the grafted tissue.

A tumour-spheroid manufacturing and cryopreservation process that yields a highly reproducible product ready for direct use in drug screening assays

If it were possible to purchase tumour-spheroids as a standardised product, ready for direct use in assays, this may contribute to greater research reproducibility, potentially reducing costs and accelerating outcomes. Herein, we describe a workflow where uniformly sized cancer tumour-spheroids are mass-produced using microwell culture, cryopreserved with high viability, and then cultured in neutral buoyancy media for drug testing. C4-2B prostate cancer or MCF-7 breast cancer cells amalgamated into uniform tumour-spheroids after 48 h of culture. Tumour-spheroids formed from 100 cells each tolerated the cryopreservation process marginally better than tumour-spheroids formed from 200 or 400 cells. Post-thaw, tumour-spheroid metabolic activity was significantly reduced, suggesting mitochondrial damage. Metabolic function was rescued by thawing the tumour-spheroids into medium supplemented with 10 µM N-Acetyl-l-cysteine (NAC). Following thaw, the neutral buoyancy media, Happy Cell ASM, was used to maintain tumour-spheroids as discrete tissues during drug testing. Fresh and cryopreserved C4-2B or MCF-7 tumour-spheroids responded similarly to titrations of Docetaxel. This protocol will contribute to a future where tumour-spheroids may be available for purchase as reliable and reproducible products, allowing laboratories to efficiently replicate and build on published research, in many cases, making tumour-spheroids simply another cell culture reagent.

Comparison of angiogenic potential in vitrified vs. slow frozen human ovarian tissue

Vitrification of ovarian tissue is a promising alternative approach to the traditional slow freezing method. Few empirical investigations have been conducted to determine the angiogenic profiles of these two freezing methods. In this study we aimed to answer the question whether one of the cryopreservation methods should be preferred based on the secretion of angiogenic factors. Tissue culture with reduced oxygen (5%) was conducted for 48 h with samples of fresh, slow frozen/thawed and vitrified/rapid warmed ovarian cortex tissue from 20 patients. From each patient, tissue was used in all three treatment groups. Tissue culture supernatants were determined regarding cytokine expression profiles of angiogenin, angiopoietin-2, epidermal growth factor, basic fibroblast growth factor, heparin binding epidermal growth factor, hepatocyte growth factor, Leptin, Platelet-derived growth factor B, placental growth factor and vascular endothelial growth factor A via fluoroimmunoassay. Apoptotic changes were assessed by TUNEL staining of cryosections and supplemented by hematoxylin and eosin and proliferating cell nuclear antigen staining. Comparing the angiogenic expression profiles of vitrified/rapid warmed tissue with slow frozen/thawed tissue samples, no significant differences were observed. Detection of apoptotic DNA fragmentation via TUNEL indicated minor apoptotic profiles that were not significantly different comparing both cryopreservation methods. Vitrification of ovarian cortical tissue does not appear to impact negatively on the expression profile of angiogenic factors and may be regarded as an effective alternative approach to the traditional slow freezing method.

Metabolic and secretory recovery of slow frozen-thawed human ovarian tissue in vitro

Within the options available for fertility preservation, cryopreservation of ovarian cortical tissue has become an important technique. Freezing and thawing procedures have been optimized to preserve tissue integrity and viability. However, the improvement of the tissue retransplantation is currently of great interest. Rapid angiogenesis is needed at the retransplantation site to accomplish sufficient blood supply to provide oxygen and nutrients. Many studies address this issue. However, we need to understand the physiology of the thawed tissue to gain further understanding of the complexities of the procedure. As freezing and thawing generally impairs cellular metabolism, we aimed to characterize the changes in metabolic activity and secretion of the angiogenic factor vascular endothelial growth factor-A (VEGF-A) of frozen-thawed ovarian cortical tissue over time. Biopsy punches of ovarian cortical tissue from patients undergoing fertility preservation were maintained in culture without freezing or after a slow-freezing and thawing procedure. VEGF-A secretion was measured after 48 h by ELISA. To examine temporary changes, metabolic activity was assessed for both fresh and frozen-thawed tissue of the same patient. Metabolic activity and VEGF-A secretion were measured at 0, 24 and 48 h in culture. Thawed ovarian cortical tissue secreted significantly less VEGF-A compared to fresh ovarian cortical tissue within 48 h of culture. After thawing, metabolic activity was significantly reduced compared to fresh ovarian cortex but over the course of 48 h, the metabolic activity recovered. Similarly, VEGF-A secretion of thawed tissue increased significantly over 48 h. Here, we have shown that it takes 48 h for ovarian cortical tissue to recover metabolically after thawing, including VEGF-A secretion.

Assay-ready Cryopreserved Cell Monolayers Enabled by Macromolecular Cryoprotectants

Cell monolayers underpin the discovery and screening of new drugs and allow for fundamental studies of cell biology and disease. However, current cryopreservation technologies do not allow cells to be stored frozen while attached to tissue culture plastic. Hence, cells must be thawed from suspension, cultured for several days or weeks, and finally transferred into multiwell plates for the desired application. This inefficient process consumes significant time handling cells, rather than conducting biomedical research or other value-adding activities. Here, we demonstrate that a synthetic macromolecular cryoprotectant enables the routine, reproducible, and robust cryopreservation of biomedically important cell monolayers, within industry-standard tissue culture multiwell plates. The cells are simply thawed with media and placed in an incubator ready to use within 24 h. Post-thaw cell recovery values were >80% across three cell lines with low well-to-well variance. The cryopreserved cells retained healthy morphology, membrane integrity, proliferative capacity, and metabolic activity; showed marginal increases in apoptotic cells; and responded well to a toxicological challenge using doxorubicin. These discoveries confirm that the cells are “assay-ready” 24 h after thaw. Overall, we show that macromolecular cryoprotectants can address a long-standing cryobiological challenge and offers the potential to transform routine cell culture for biomedical discovery.

Dynamic in vitro culture of cryopreserved-thawed human ovarian cortical tissue using a microfluidics platform does not improve early folliculogenesis

Current strategies for fertility preservation include the cryopreservation of embryos, mature oocytes or ovarian cortical tissue for autologous transplantation. However, not all patients that could benefit from fertility preservation can use the currently available technology. In this regard, obtaining functional mature oocytes from ovarian cortical tissue in vitro would represent a major breakthrough in fertility preservation as well as in human medically assisted reproduction. In this study, we have used a microfluidics platform to culture cryopreserved-thawed human cortical tissue for a period of 8 days and evaluated the effect of two different flow rates in follicular activation and growth. The results showed that this dynamic system supported follicular development up to the secondary stage within 8 days, albeit with low efficiency. Surprisingly, the stromal cells in the ovarian cortical tissue were highly sensitive to flow and showed high levels of apoptosis when cultured under high flow rate. Moreover, after 8 days in culture, the stromal compartment showed increase levels of collagen deposition, in particular in static culture. Although microfluidics dynamic platforms have great potential to simulate tissue-level physiology, this system still needs optimization to meet the requirements for an efficient in vitro early follicular growth.