Mitochondrial Replacement Therapy Research Articles

Nuclear transfer leads to aberrant cell cycle regulation and translation, as determined by gene expression, and selection of mitochondrial DNA in porcine blastocysts

Abstract Nuclear transfer technologies, such as metaphase II spindle transfer (MII-ST), are being developed to overcome poor oocyte quality and prevent children from acquiring severe mitochondrial DNA (mtDNA) disease. However, it is unclear whether these technologies perturb gene expression; and mtDNA carryover can be reduced to minimal levels. Using our pig model, we isolated individual karyoplasts with limited mtDNA carryover (306 ± 49 copies) from mature oocytes. Firstly, we reintroduced the spindle into its original cytoplast (autologous), fertilised, and cultured the resultant embryos to the hatching blastocyst stage of development. Following RNA-seq, 64 genes were differentially expressed at FDR < 0.05; and 1327 genes at P < 0.05. Pathways associated with cell cycle and epigenetic regulation and genes associated with nuclear-mitochondrial interactions were upregulated whilst protein translation pathways were downregulated. We then transferred karyoplasts to third party cytoplasts (heterologous) and undertook mtDNA next generation sequencing of 2-cell to hatching blastocyst stage preimplantation embryos. Nine of 20 embryos possessed two mitochondrial genomes. Our outcomes show that autologous nuclear transfer alone significantly changes hatching blastocyst gene expression; very low levels of mtDNA carryover can be preferentially replicated during early development; and nuclear and mitochondrial synchrony has not been reestablished.

Mitochondrial donation as a mechanism of participation by mesenchymal stromal cells in regenerative processes

Mesenchymal stromal cells (MSCs) are universal regulators of regenerative processes due to their ability to secrete regulatory molecules or replace dead cells through differentiation in the appropriate direction. Recently, another mechanism for the beneficial effects of MSCs on damaged tissue has been discovered, such as the transfer of mitochondria into its cells in response to stress signals. MSCs can transfer mitochondria through tunneling nanotubes that form a communication bridge between cells, through gap junctions, by release as part of extracellular vesicles or in free form, and as a result of complete or partial fusion with recipient cells. In damaged cells that received mitochondria from MSCs, impaired energy metabolism is restored and oxidative stress is reduced, which is accompanied by increased survival, and in some cases also increased proliferation or a change in differentiation status. The restoration of energy after the transfer of mitochondria from MSCs has a beneficial effect on the functional activity of recipient cells and suppresses inflammatory reactions. A significant contribution of the MSC mitochondrial donation to the therapeutic efficacy of MSCs has been repeatedly demonstrated in models of damage to various organs in experimental animals. This stimulates the search for methods to enhance the process of mitochondrial donation. However, it should be taken into account that MSCs are able to transfer mitochondria to malignant cells as well, thereby stimulating tumor growth and increasing its resistance to chemotherapy. These data make it necessary to evaluate the prospects for the use of MSCs in cell therapy with caution. On the other hand, they can serve as a basis for the search for new therapeutic targets in the treatment of oncological diseases.

Mitochondrial replacement in the English-language print media: continuity and change in metaphors and social representations

In May 2023, The Guardian announced that babies had been born through mitochondrial replacement therapy (MRT). MRT and its ethical and legal implications have been discussed in the media for over a decade. These discussions have been examined by social scientists and communication scholars. In this article, we seek to determine whether and, if so, how social representations have changed since this announcement. Using thematic analysis and social representations theory, we studied a corpus of 70 English language newspaper articles. Results show three thematic dichotomies: (1) moderation vs. sensationalism; (2) ontologising vs. de-ontologising MRT; and (3) using metaphors for persuasion vs. explanation. The societal concern representation largely dominated reporting around 2015 and the hope and opportunity representation was prominent in current reporting. We argue that the hope representation may facilitate greater patient and public acceptance of MRT but that it may also limit awareness, understanding and discussion of its possible risks and limitations.

Pregnancy in women with mitochondrial disease-A literature review and suggested guidance for preconception and pregnancy care.

Mitochondrial donation to reduce the risk of primary mitochondrial disease transmission from mother to child is now permitted under Australian law as part of a clinical trial. The energy demands of pregnancy have the potential to worsen mitochondrial disease symptoms and severity in affected women. We conducted a systematic literature review on mitochondrial disease in pregnancy; five cohort studies and 19 case reports were included. For many women with mitochondrial disease, pregnancy does not have a negative effect on health status. However, serious adverse outcomes may occur. We provide suggested guidelines for preconception counselling and antenatal care.

Mitochondrial genome variants associated with amyotrophic lateral sclerosis and their haplogroup distribution.

Amyotrophic lateral sclerosis (ALS) may be familial or sporadic, and twin studies have revealed that even sporadic forms have a significant genetic component. Variants in 55 nuclear genes have been associated with ALS and although mitochondrial dysfunction is observed in ALS, variants in mitochondrial genomes (mitogenomes) have not yet been tested for association with ALS. The aim of this study was to determine whether mitogenome variants are associated with ALS. We conducted a genome-wide association study (GWAS) in mitogenomes of 1965 ALS patients and 2547 controls. We identified 51 mitogenome variants with p values <10-7, of which 13 had odds ratios (ORs) >1, in genes RNR1, ND1, CO1, CO3, ND5, ND6, and CYB, while 38 variants had OR <1 in genes RNR1, RNA2, ND1, ND2, CO2, ATP8, ATP6, CO3, ND3, ND4, ND5, ND6, and CYB. The frequencies of haplogroups H, U, and L, the most frequent in our ALS data set, were the same in different onset sites (bulbar, limb, spinal, and axial). Also, intra-haplogroup GWAS revealed unique ALS-associated variants in haplogroups L and U. Our study shows that mitogenome single nucleotide variants (SNVs) are associated with ALS and suggests that these SNVs could be included in routine genetic testing for ALS and that mitochondrial replacement therapy has the potential to serve as a basis for ALS treatment.

Mitochondria as therapeutic targets in assisted reproduction.

Mitochondria are essential organelles with specialized functions, which play crucial roles in energy production, calcium homeostasis, and programmed cell death. In oocytes, mitochondrial populations are inherited maternally and are vital for developmental competence. Dysfunction in mitochondrial quality control mechanisms can lead to reproductive failure. Due to their central role in oocyte and embryo development, mitochondria have been investigated as potential diagnostic and therapeutic targets in assisted reproduction. Pharmacological agents that target mitochondrial function and show promise in improving assisted reproduction outcomes include antioxidant coenzyme Q10 and mitoquinone, mammalian target of rapamycin signaling pathway inhibitor rapamycin, and nicotinamide mononucleotide. Mitochondrial replacement therapies (MRTs) offer solutions for infertility and mitochondrial disorders. Autologous germline mitochondrial energy transfer initially showed promise but failed to demonstrate significant benefits in clinical trials. Maternal spindle transfer (MST) and pronuclear transfer hold potential for preventing mitochondrial disease transmission and improving oocyte quality. Clinical trials of MST have shown promising outcomes, but larger studies are needed to confirm safety and efficacy. However, ethical and legislative challenges complicate the widespread implementation of MRTs.

The three-parent baby: Medicolegal, forensic and ethical concerns.

In the recent past, human genetics and in vitro fertilization (IVF) have undergone various advances to combat with several congenital and developmental disorders. These advances are a boon for the families and patients who were restricted from having a child due to one or the other reasons. One such reason is the mitochondrial DNA (mtDNA) mutations, which are definitely transmitted from the mother to the child due to uniparental/maternal inheritance of mitochondria. Depending upon the range of the mutation (mutation loads) present, the mtDNA mutation leads to various devitalizing to fatal disorders, all of which are incurable. Scientists and researchers developed a technique known as mitochondrial donation technique or mitochondrial replacement therapy (MRT) to combat with the mtDNA mutations. The technique relies on the replacement of faulty mitochondria in the mother's egg with the normal wild-type from a donor female resulting in a "three-parent baby." On the other side, forensic scientists and anthropologists continuously explore the mtDNA in various medicolegal cases and in uncoupling the mystery of human origin and migration respectively. In this regard, we explored the genetic, forensic and ethical aspects of a "three-parent baby." The present communication also attempts to highlight the importance and limitations of the MRT technique/three-parent baby in a medicolegal context.

Carcinoma-associated mesenchymal stem cells promote ovarian cancer heterogeneity and metastasis through mitochondrial transfer

Ovarian cancer is characterized by early metastatic spread. This study demonstrates that carcinoma-associated mesenchymal stromal cells (CA-MSCs) enhance metastasis by increasing tumor cell heterogeneity through mitochondrial donation. CA-MSC mitochondrial donation preferentially occurs in ovarian cancer cells with low levels of mitochondria ("mito poor"). CA-MSC mitochondrial donation rescues the phenotype of mito poor cells, restoring their proliferative capacity, resistance to chemotherapy, and cellular respiration. Receipt of CA-MSC-derived mitochondria induces tumor cell transcriptional changes leading to the secretion of ANGPTL3, which enhances the proliferation of tumor cells without CA-MSC mitochondria, thus amplifying the impact of mitochondrial transfer. Donated CA-MSC mitochondrial DNA persisted in recipient tumor cells for at least 14days. CA-MSC mitochondrial donation occurs invivo, enhancing tumor cell heterogeneity and decreasing mouse survival. Collectively, this work identifies CA-MSC mitochondrial transfer as a critical mediator of ovarian cancer cell survival, heterogeneity, and metastasis and presents a unique therapeutic target in ovarian cancer.

O-057 Newly identified female mutations causing failed fertilization

Abstract Over the past decade, advancements in next-generation sequencing technology, alongside reduced costs, and the rising demand for infertility medical care, have resulted in the discovery of new genes and genetic variants linked to infertility conditions. Phenotypes of ICSI failure, such as oocyte maturation arrest (OMA), fertilization failure (FF) and embryo developmental arrest (EDA), can now be attributed to male or female genetic causes. This represents a transformative shift in patient treatment, allowing the identification of some cases previously classified as unexplained infertility, thereby reducing patient stress. Moreover, it facilitates personalized treatment recommendations, as well as paves the way for the exploration of novel treatment options, thus expanding research opportunities. This talk will review the genetic causes of FF following ICSI, with the main focus on the newly identified female causes, as well as give an update on current diagnostic tests and treatment options for this infertility condition. FF after ICSI still occurs in 1-3% of ICSI cycles, primarily due to oocyte activation deficiency (OAD). Defects in the male PLCζ protein, responsible of inducing calcium oscillations during oocyte activation, have long been known as the leading cause of OAD. Recent discoveries have identified genetic variants in the male genes ACTL7A, ACTL9 and IQCN, which also reduce PLCζ protein content in sperm cells and thus, contribute to FF after ICSI. Additionally, for the first time in 2018, mutations in a female gene (WEE2) crucial for oocyte activation were identified. WEE2 is an oocyte kinase that acts downstream the calcium release during fertilization. Interestingly, genetic variants in other female genes, such as PATL2, TUBB8 and CDC20 associated mainly to OMA and TLE6 and NLRP5 associated mainly to EDA, have also been described to cause failed fertilization in some patients. Determining whether the deficiency lies in sperm- or oocyte-related genes is crucial for tailoring the most effective treatment for FF after ICSI. For sperm-related factors, assisted oocyte activation (AOA), which consists in the artificial induction of calcium oscillations using calcium ionophores, has proven highly beneficial. However, most patients with oocyte-factors do not benefit from AOA (e.g. patients with WEE2 variants). In this regard, wild-type cRNA injection of the defected protein has been shown to rescue fertilization. A more generalist approach, such as maternal spindle transfer, which consists in replacing poor-quality oocyte cytoplasm with healthy cytoplasm from a donor oocyte, represents a potential treatment for these patients, as recently demonstrated in infertile females with repeated IVF failures. Nevertheless, further research into the safety of these procedures is needed before clinical application, and for now, gamete donation should be considered when facing female-related FF.

Autophagy modulation effect on homotypic transfer of intracellular components via tunneling nanotubes in mesenchymal stem cells

BackgroundRecent studies have proved the role of autophagy in mesenchymal stem cell (MSCs) function and regenerative properties. How and by which mechanism autophagy modulation can affect the juxtacrine interaction of MSCs should be addressed. Here, the role of autophagy was investigated in the formation of tunneling nanotubes (TNTs) and homotypic mitochondrial donation.MethodsMSCs were incubated with 15 µM Metformin (Met) and/or 3 µM 3-methyladenine (3-MA) for 48 h. The formation of TNTs was assessed using bright-field and SEM images. The mitochondria density and ΔΨ values were monitored using flow cytometry analysis. Using RT-PCR and protein array, the close interaction and shared mediators between autophagy, apoptosis, and Wnt signaling pathways were also monitored. The total fatty acid profile was assessed using gas chromatography.ResultData indicated the increase of TNT length and number, along with other cell projections after the induction of autophagy while these features were blunted in 3-MA-treated MSCs (p < 0.05). Western blotting revealed the significant reduction of Rab8 and p-FAK in 3-MA-treated MSCs (p < 0.05), indicating the inhibition of TNT assembly and vesicle transport. Likewise, the stimulation of autophagy increased autophagic flux and mitochondrial membrane integrity compared to 3-MA-treated MSCs. Despite these findings, protein levels of mitochondrial membrane Miro1 and 2 were unchanged after autophagy inhibition/stimulation (p > 0.05). We found that the inhibition/stimulation of autophagy can affect the protein, and transcription levels of several mediators related to Wnt and apoptosis signaling pathways involved in different cell bioactivities. Data confirmed the profound increase of mono and polyunsaturated/saturated fatty acid ratio in MSCs exposed to autophagy stimulator.ConclusionsIn summary, autophagy modulation could affect TNT formation which is required for homotypic mitochondrial donation. Thus, the modulation of autophagy creates a promising perspective to increase the efficiency of cell-based therapies.

Enucleated egg donation: why is it important to understand the attitudes of women on donating enucleated eggs?

Enucleated egg donation is increasingly used for mitochondrial replacement therapy and in assisted conception to improve the success rate for women with recurrent IVF failure. With the possibility of a future increase in demand for enucleated egg donation, it is important to understand the attitudes of the general public and egg donors towards it. This Viewpoint elaborates on the general public's and donors’ perspectives on important aspects of enucleated egg donation that need to be explored, and points towards the areas that need to be researched in the future.

Identification of Molecular Profile of Ear Fibroblasts Derived from Spindle-Transferred Holstein Cattle with Ooplasts from Taiwan Yellow Cattle under Heat Stress.

Global warming has a significant impact on the dairy farming industry, as heat stress causes reproductive endocrine imbalances and leads to substantial economic losses, particularly in tropical-subtropical regions. The Holstein breed, which is widely used for dairy production, is highly susceptible to heat stress, resulting in a dramatic reduction in milk production during hot seasons. However, previous studies have shown that cells of cows produced from reconstructed embryos containing cytoplasm (o) from Taiwan yellow cattle (Y) have improved thermotolerance despite their nuclei (n) being derived from heat-sensitive Holstein cattle (H). Using spindle transfer (ST) technology, we successfully produced ST-Yo-Hn cattle and proved that the thermotolerance of their ear fibroblasts is similar to that of Y and significantly better than that of H (p < 0.05). Despite these findings, the genes and molecules responsible for the different sensitivities of cells derived from ST-Yo-Hn and H cattle have not been extensively investigated. In the present study, ear fibroblasts from ST-Yo-Hn and H cattle were isolated, and differentially expressed protein and gene profiles were compared with or without heat stress (hs) (42 °C for 12 h). The results revealed that the relative protein expression levels of pro-apoptotic factors, including Caspase-3, -8, and -9, in the ear fibroblasts from the ST-Yo-Hn-hs group were significantly lower (p < 0.05) than those from the H-hs group. Conversely, the relative expression levels of anti-apoptotic factors, including GNA14 protein and the CRELD2 and PRKCQ genes, were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Analysis of oxidative phosphorylation-related factors revealed that the relative expression levels of the GPX1 gene and Complex-I, Complex-IV, CAT, and PGLS proteins were significantly higher (p < 0.05) in the ear fibroblasts from the ST-Yo-Hn-hs group compared to those from the H-hs group. Taken together, these findings suggest that ear fibroblasts from ST-Yo-Hn cattle have superior thermotolerance compared to those from H cattle due to their lower expression of pro-apoptotic factors and higher expression of oxidative phosphorylation and antioxidant factors. Moreover, this improved thermotolerance is attributed, at least partially, to the cytoplasm derived from more heat-tolerant Y cattle. Hence, using ST technology to produce more heat-tolerant H cattle containing Y cytoplasm could be a feasible approach to alleviate the negative impacts of heat stress on dairy cattle in tropical-subtropical regions.

‘Recombining’ biological motherhoods. Towards two ‘complete’ biological mothers

Within feminist literature from the early 1970s to this day, assisted reproductive technologies have been largely known to divide, replace or eliminate biological motherhood. For example, while in the past...

Implications of Law’s Response to Mitochondrial Donation

Changes to Australian law in 2022 made Australia the second country to expressly permit the clinical use of mitochondrial donation (MD), a technology that makes heritable changes to the human genome. This paper considers these changes in the context of Australia’s broader controls on human embryo use to provide insights into future regulatory responses to other emerging genetic technologies, which could be used in reproduction.

Abstract B085: Carcinoma-associated mesenchymal stem cells promote high-grade serous ovarian cancer metastasis and drive tumor heterogeneity at the metastatic site through direct mitochondrial transfer

Abstract High-grade serous ovarian cancer (HGSC) is the most common and lethal form of ovarian cancer, accounting for over 70% of ovarian cancer cases. HGSC mortality is largely driven by early and diffuse transcoelomic spread from the primary site throughout the peritoneal cavity, resulting in roughly three-quarters of cases presenting with advanced stage disease at time of diagnosis. Following detachment from the primary tumor, disseminated ovarian cancer cells are spread by the peritoneal fluid and ascites where they must adapt to their new microenvironment to survive and successfully form metastases. Crucial to this spread is the formation of multicellular aggregates containing both cancer and non-malignant stromal cells, which enhance cancer cell survival and are associated with poor clinical outcome. While most studies on HGSC multicellular aggregates have focused on ovarian cancer cells alone, the interactions between ovarian cancer cells and other non-malignant cells have yet to be fully elucidated. Prior work by our group have shown that stromal-progenitor cells, termed carcinoma-associated mesenchymal stem/stromal cells (CA-MSCs), enhance HGSC metastasis through direct cellular interaction and formation of heterocellular CA-MSC:cancer cell complexes. Here we demonstrate CA-MSCs enhance metastasis by preferentially donating their mitochondria to cancer cells with the least amount of endogenous mitochondria content (‘mito poor’ cancer cells), increasing their ability to survive and driving tumor heterogeneity at the metastatic site in vivo. Mito poor cancer cells were shown to have decreased proliferative capacity, increased sensitivity to platinum-based chemotherapy and display decreased oxidative phosphorylation (OXPHOS) compared to ‘mito rich’ cancer cells. Primary patient-derived CA-MSCs rescue this vulnerable phenotype by increasing proliferation, chemoresistance and OXPHOS in mito poor cancer cells. These findings were validated in a fully autologous system using CA-MSCs and cancer cells derived from the same patient to prevent confounding effects of cellular response to foreign organelle/DNA. Through lentiviral knockdown of the mitochondrial motor protein MIRO1 we further demonstrate mitochondrial transfer is necessary for CA-MSC-mediated rescue of mito poor cancer cells. Further, we developed a haplotype-specific quantification of mitochondrial DNA to differentiate CA-MSC from endogenous cancer cell mitochondria which was used to quantify the amount of CA-MSC mitochondrial donation and demonstrate donated mitochondria persist in cancer cells up to 14 days. Importantly, CA-MSC mitochondrial donation occurred in vivo and was associated with decreased survival in an orthotopic ovarian cancer murine model. Genomic barcoding was used to quantify tumor cell clonal heterogeneity; using this system we demonstrate CA-MSC mitochondrial donation significantly enhance tumor cell heterogeneity at the metastatic site in vivo. Collectively, we report CA-MSC mitochondrial transfer as a driver of HGSC progression, heterogeneity and metastasis. Citation Format: Leonard G. Frisbie, Catherine A. Pressimone, Roja Baruwal, Geyon L. Garcia, Zanib Javed, Claudette St. Croix, Simon Watkins, Michael Calderone, Huda I. Atiya, Nadine Hempel, Alexander Pearson, Lan G. Coffman. Carcinoma-associated mesenchymal stem cells promote high-grade serous ovarian cancer metastasis and drive tumor heterogeneity at the metastatic site through direct mitochondrial transfer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B085.

What importance do donors and recipients attribute to the nuclear DNA-related genetic heritage of oocyte donation?

How do oocyte donors and recipients perceive the genetic link related to the transfer of nuclear DNA between donors and offspring? Whether they are donors or recipients, individuals attach great importance to the transmission of their genetic heritage, since 94.5% would opt for the pronuclear transfer method to preserve this genetic link in the context of oocyte donation. Since 1983, the use of oocyte donation has increased worldwide. Performed in France since the late 1980s and initially offered to women with premature ovarian insufficiency, its indications have progressively expanded and now it is proposed in many indications to prevent the transmission of genetically inherited diseases. This has resulted in an increase in the waiting time for access to oocyte donation due to the difficulty in recruiting oocyte donors in French ART centres. Several articles have discussed how to fairly distribute donor oocytes to couples, but few have interviewed women in the general population to record their feelings about oocyte donation, as either the donor or recipient and the importance given to the genetic link between the oocyte donors and the children born. Mitochondrial replacement therapy (MRT) is a technique originally developed for women at risk of transmitting a mitochondrial DNA mutation. Recently, MRT has been considered for embryo arrest and oocyte rejuvenation as it could help females to reproduce with their own genetic material through the transfer of their oocyte nucleus into a healthy donor oocyte cytoplasm. We conducted an opinion survey from January 2021 to December 2021, during which 1956 women completed the questionnaire. Thirteen participants were excluded from the analysis due to incomplete responses to all the questions. Consequently, 1943 women were included in the study. We specifically developed a questionnaire for this study, which was created and distributed using the Drag'n Survey® software. The questionnaire consisted of 21 items presented alongside a video created with whiteboard animation software. The aim was to analyse whether certain factors, such as age, education level, marital status, number of children, use of ART for pregnancy, video viewing, and knowledge about oocyte donation, were associated with feelings towards oocyte donation, by using a univariate conditional logistic regression model. This statistical method was also used to assess whether women would be more inclined to consider oocyte donation with the pronuclear transfer technique rather than the whole oocyte donation. All parameters found to be statistically significant in the univariate analysis were subsequently tested in a multivariate model using logistic regression. Most women were concerned about the biological genetic contribution of the donated oocyte (94.8%). The most common reason for a women's reluctance to donate their oocytes was their unwillingness to pass on their genetic material (33.3%). Nearly 70% of women who were initially hesitant to donate their oocytes indicated that they would reconsider their decision if the oocyte donation was conducted using donated cytoplasm and the pronuclear transfer technique. Concomitantly, >75% of the respondents mentioned that it would be easier to receive a cytoplasm donation. The largest proportion of the population surveyed (94.5%) expressed their support for its legalization. In this study, a substantial portion of the responses came from individuals with medical or paramedical backgrounds, potentially introducing a recruitment bias among potential donors. The rate of missing responses to the question regarding the desire to become an oocyte donor was 13.6%, while the question about becoming an oocyte cytoplasm donor had a missing response rate of 23%. These missing responses may introduce a bias in the interpretation of the data. This study was the first to demonstrate that, for the French population studied, the combination of oocyte cytoplasm donation with pronuclear transfer could offer a promising approach to enhance the acceptance of oocyte donation for both the donor and the recipient. No external funding was used for this study. The authors have no conflicts of interest. N/A.

Angiogenic activity of mitochondria; beyond the sole bioenergetic organelle.

Angiogenesis is a complex process that involves the expansion of the pre-existing vascular plexus to enhance oxygen and nutrient delivery and is stimulated by various factors, including hypoxia. Since the process of angiogenesis requires a lot of energy, mitochondria play an important role in regulating and promoting this phenomenon. Besides their roles as an oxidative metabolism base, mitochondria are potential bioenergetics organelles to maintain cellular homeostasis via sensing alteration in oxygen levels. Under hypoxic conditions, mitochondria can regulate angiogenesis through different factors. It has been indicated that unidirectional and bidirectional exchange of mitochondria or their related byproducts between the cells is orchestrated via different intercellular mechanisms such as tunneling nanotubes, extracellular vesicles, and gap junctions to maintain the cell homeostasis. Even though, the transfer of mitochondria is one possible mechanism by which cells can promote and regulate the process of angiogenesis under reperfusion/ischemia injury. Despite the existence of a close relationship between mitochondrial donation and angiogenic response in different cell types, the precise molecular mechanisms associated with this phenomenon remain unclear. Here, we aimed to highlight the possible role of mitochondria concerning angiogenesis, especially the role of mitochondrial transport and the possible relation of this transfer with autophagy, the housekeeping phenomenon of cells, and angiogenesis.

Pronuclear transfer rescues poor embryo development of in vitro-grown secondary mouse follicles.

Pronuclear transfer rescues poor embryo development of in vitro-grown secondary mouse follicles.

Generation of mitochondrial replacement monkeys by female pronucleus transfer.

Mutations in mitochondrial DNA (mtDNA) are maternally inherited and have the potential to cause severe disorders. Mitochondrial replacement therapies, including spindle, polar body, and pronuclear transfers, are promising strategies for preventing the hereditary transmission of mtDNA diseases. While pronuclear transfer has been used to generate mitochondrial replacement mouse models and human embryos, its application in non-human primates has not been previously reported. In this study, we successfully generated four healthy cynomolgus monkeys ( Macaca fascicularis) via female pronuclear transfer. These individuals all survived for more than two years and exhibited minimal mtDNA carryover (3.8%-6.7%), as well as relatively stable mtDNA heteroplasmy dynamics during development. The successful establishment of this non-human primate model highlights the considerable potential of pronuclear transfer in reducing the risk of inherited mtDNA diseases and provides a valuable preclinical research model for advancing mitochondrial replacement therapies in humans.

Three to one – an ethicolegal outline of mitochondrial donation in the South African context

Mitochondrial donation or mitochondrial transfer enables a woman with mitochondrial disease to have a genetically related child without transmitting the disease to the child. The techniques used for mitochondrial donation or transfer which are maternal spindle transfer or pro-nuclei transfer, require three gametes to ultimately produce a healthy embryo. Both these techniques result in the child inheriting nuclear DNA from the intending parents and mitochondrial DNA from the female donor. Following the legalisation of mitochondrial donation in the UK, after a rigorous process of scientific and ethical review, and the birth of another baby using the technique, coupled with the fact that there is no cure for mitochondrial disease, suggests that it is prudent for us to consider this reproductive intervention and its application in the South African setting. In addition, the 2019 UNESCO Report of the International Bioethics Committee (IBC) on assisted reproductive technologies (ART) and parenthood, encourages debate on changes in models of parenthood influenced by ART including the emergence of new models of families and forms of parenthood that extend beyond the classical rule of mater semper certa est (the mother is always known). ART, in particular mitochondrial donation, challenges this rule. The aim of this paper is to provide an outline of the legal and ethical positions of mitochondrial donation and resume the discussion with specific focus on the South African context.