Functionalization of mesoporous silica nanoparticles with a cell-penetrating peptide to target mammalian sperm in vitro

Rethinking the application of nanoparticles in women's reproductive health and assisted reproduction

Nanoparticles and nanotechnology may present opportunities to revolutionize the prevention, treatment and diagnosis of a range of reproductive health conditions in women. These technologies are also used to improve outcomes of assisted reproductive technology. We highlight a range of these potential clinical uses of nanoparticles for polycystic ovary syndrome, endometriosis, uterine fibroids and sexually transmitted infections, considering in vitro and in vivo studies along with clinical trials. In addition, we discuss applications of nanoparticles in assisted reproductive technology, including sperm loading, gamete and embryo preservation and preventing preterm birth. Finally, we present some of the concerns associated with the medical use of nanoparticles, identifying routes for further exploration before nanoparticles can be applied to women's reproductive health in the clinic.

ZIF-8 Nanoparticle: A Valuable Tool for Improving Gene Delivery in Sperm-Mediated Gene Transfer

Metal-organic frameworks (MOFs) are porous materials with unique characteristics that make them well-suited for drug delivery and gene therapy applications. Among the MOFs, zeolitic imidazolate framework-8 (ZIF-8) has emerged as a promising candidate for delivering exogenous DNA into cells. However, the potential of ZIF-8 as a vector for sperm-mediated gene transfer (SMGT) has not yet been thoroughly explored.This investigation aimed to explore the potential of ZIF-8 as a vector for enhancing genetic transfer and transgenesis rates by delivering exogenous DNA into sperm cells. To test this hypothesis, we employed ZIF-8 to deliver a plasmid expressing green fluorescent protein (GFP) into mouse sperm cells and evaluated the efficiency of DNA uptake. Our findings demonstrate that ZIF-8 can efficiently load and deliver exogenous DNA into mouse sperm cells, increasing GFP expression in vitro. These results suggest that ZIF-8 is a valuable tool for enhancing genetic transfer in SMGT, with important implications for developing genetically modified animals for research and commercial purposes. Additionally, our study highlights the potential of ZIF-8 as a novel class of vectors for gene delivery in reproductive biology.Overall, our study provides a foundation for further research into using ZIF-8 and other MOFs as gene delivery systems in reproductive biology and underscores the potential of these materials as promising vectors for gene therapy and drug delivery.

Applications of advances in mRNA-based platforms as therapeutics and diagnostics in reproductive technologies

The recent COVID-19 pandemic led to many drastic changes in not only society, law, economics, but also in science and medicine, marking for the first time when drug regulatory authorities cleared for use mRNA-based vaccines in the fight against this outbreak. However, while indeed representing a novel application of such technology in the context of vaccination medicine, introducing RNA into cells to produce resultant molecules (proteins, antibodies, etc.) is not a novel principle. It has been common practice to introduce/inject mRNA into oocytes and embryos to inhibit, induce, and identify several factors in a research context, while such aspects have also been proposed as potential therapeutic and diagnostic applications to combat infertility in humans. Herein, we describe key areas where mRNA-based platforms have thus far represented potential areas of clinical applications, describing the advantages and limitations of such applications. Finally, we also discuss how recent advances in mRNA-based platforms, driven by the recent pandemic, may stand to benefit the treatment of infertility in humans. We also present brief future directions as to how we could utilise recent and current advancements to enhance RNA therapeutics within reproductive biology, specifically with relation to oocyte and embryo delivery.

Protein Transduction Domain-Mediated Delivery of Recombinant Proteins and In Vitro Transcribed mRNAs for Protein Replacement Therapy of Human Severe Genetic Mitochondrial Disorders: The Case of Sco2 Deficiency

Mitochondrial disorders represent a heterogeneous group of genetic disorders with variations in severity and clinical outcomes, mostly characterized by respiratory chain dysfunction and abnormal mitochondrial function. More specifically, mutations in the human SCO2 gene, encoding the mitochondrial inner membrane Sco2 cytochrome c oxidase (COX) assembly protein, have been implicated in the mitochondrial disorder fatal infantile cardioencephalomyopathy with COX deficiency. Since an effective treatment is still missing, a protein replacement therapy (PRT) was explored using protein transduction domain (PTD) technology. Therefore, the human recombinant full-length mitochondrial protein Sco2, fused to TAT peptide (a common PTD), was produced (fusion Sco2 protein) and successfully transduced into fibroblasts derived from a SCO2/COX-deficient patient. This PRT contributed to effective COX assembly and partial recovery of COX activity. In mice, radiolabeled fusion Sco2 protein was biodistributed in the peripheral tissues of mice and successfully delivered into their mitochondria. Complementary to that, an mRNA-based therapeutic approach has been more recently considered as an innovative treatment option. In particular, a patented, novel PTD-mediated IVT-mRNA delivery platform was developed and applied in recent research efforts. PTD-IVT-mRNA of full-length SCO2 was successfully transduced into the fibroblasts derived from a SCO2/COX-deficient patient, translated in host ribosomes into a nascent chain of human Sco2, imported into mitochondria, and processed to the mature protein. Consequently, the recovery of reduced COX activity was achieved, thus suggesting the potential of this mRNA-based technology for clinical translation as a PRT for metabolic/genetic disorders. In this review, such research efforts will be comprehensibly presented and discussed to elaborate their potential in clinical application and therapeutic usefulness.

Development of a novel PTD-mediated IVT-mRNA delivery platform for potential protein replacement therapy of metabolic/genetic disorders

The potential clinical applications of the powerful in vitro-transcribed (IVT)-mRNAs, to restore defective protein functions, strongly depend on their successful intracellular delivery and transient translation through the development of safe and efficient delivery platforms. In this study, an innovative (international patent-pending) methodology was developed, combining the IVT-mRNAs with the protein transduction domain (PTD) technology, as an efficient delivery platform. Based on the PTD technology, which enables the intracellular delivery of various cargoes intracellularly, successful conjugation of a PTD to the IVT-mRNAs was achieved and evaluated by band-shift assay and NMR spectroscopy. In addition, the PTD-IVT-mRNAs were applied and evaluated in two protein-disease models, including the mitochondrial disorder fatal infantile cardioencephalomyopathy and cytochrome c oxidase (COX) deficiency (attributed to SCO2 gene mutations) and β-thalassemia. The PTD-IVT-mRNA of SCO2 was successfully transduced and translated to the corresponding Sco2 protein inside the primary fibroblasts of a SCO2/COX-deficient patient, whereas the PTD-IVT-mRNA of β-globin was transduced and translated in bone marrow cells, derived from three β-thalassemic patients. The transducibility and the structural stability of the PDT-IVT-mRNAs, in both cases, were confirmed at the RNA and protein levels. We propose that our novel delivery platform could be clinically applicable as a protein therapy for metabolic/genetic disorders.

Degradable and colloidally stable zwitterionic-functionalized silica nanoparticles

Aim: This work is focused on obtaining degradable mesoporous silica nanoparticles (DMSNs) which are able to maintain their colloidal stability in complex biological media. Materials & methods: DMSNs were synthesized using different ratios of disulfide organosilane (degradable structural moiety) and further functionalized with sulfobetaine silane (SBS) to enhance colloidal stability and improve biological compatibility. Results: There was a clear trade-off between nanoparticle degradability and colloidal stability, since full optimization of the degradation process generated unstable particles, while enhancing colloidal stability resulted in poor DMSNs degradation. It was also shown that acidic pH improved particle degradation which is commonly triggered by reduction stimulus. Conclusion: A chemical composition window was found where DMSNs presented satisfactory colloidal stability in biologically relevant medium, meaningful degradation profiles and high biocompatibility.

Exosomes derived from HEK293T cells interact in an efficient and noninvasive manner with mammalian sperm in vitro

Aim: To investigate exosomes as a noninvasive delivery tool for mammalian sperm. Materials & Methods: Exosomes were isolated from HEK293T cells and co-incubated with boar sperm in vitro. Results: Internalized exosomes were detected within 10 min of co-incubation. Computer-assisted sperm analysis and flow cytometry demonstrated that even after 5-h of exposure to exosomes, there were no significant deleterious effects with regard to sperm motility, viability, membrane integrity and mitochondrial membrane potential (p > 0.05), thus indicating that exosomes did not interfere with basic sperm function. Conclusion: HEK293T-derived exosomes interacted with boar sperm without affecting sperm function. Exosomes represent a versatile and promising research tool for studying sperm biology and provide new options for the diagnosis and treatment of male infertility.

Applications of omics and nanotechnology to improve pig embryo production in vitro

An appropriate environment to optimize porcine preimplantation embryo production in vitro is required as genetically modified pigs have become indispensable for biomedical research and agriculture. To provide suitable culture conditions, omics technologies have been applied to elucidate which metabolic substrates and pathways are involved during early developmental processes. Metabolomic profiling and transcriptional analysis comparing in vivo- and in vitro-derived embryos have demonstrated the important role of amino acids during preimplantation development. Transcriptional profiling studies have been helpful in assessing epigenetic reprogramming agents to allow for the correction of gene expression during the cloning process. Along with this, nanotechnology, which is a highly promising field, has allowed for the use of engineered nanoplatforms in reproductive biology. A growing number of studies have explored the use of nanoengineered materials for sorting, labeling, and targeting purposes; which demonstrates their potential to become one of the solutions for precise delivery of molecules into gametes and embryos. Considering the contributions of omics and the recent progress in nanoscience, in this review, we focused on their emerging applications for current in vitro pig embryo production systems to optimize the generation of genetically modified animals.

Treatment of boar sperm with nanoparticles for improved fertility

Continuous progress in nanoscience has allowed the synthesis of various nanoscale particles, known as nanoparticles or nanomaterials which, by harnessing unique physico-chemical properties, are crucial for multiple bio-applications. Despite the revealed toxicity (nanotoxicity) of nanoparticles in various in vitro and in vivo studies, their careful design for biocompatibility and effective interactions with single-celled and multi-cellular organisms has permitted their use in several fields of research and biomedicine. The various nanoparticles synthesized and applied in the veterinary sciences, including reproductive biology, have shown potential to influence routine practices in animal production systems. These include post-collection manipulation of semen and the protection of high-quality spermatozoa to extend their preservation, and to improve sperm-related biotechnologies such as sperm-mediated gene transfer, sperm sorting, sex-sorting, and cryopreservation. Therefore, the application of nanotechnology-based tools to semen may enhance assisted reproductive technologies for biomedical applications and improve economic productivity for farmers. Here, we review the efficacy of available techniques and emerging tools of nanotechnology that might be useful for further selection of high quality boar spermatozoa and productivity improvement.

Perspectives of nanotechnology in male fertility and sperm function

Recent advances in nanotechnology have tremendously expanded its possible applications in biomedicine. Although, the effects of nanoparticles (NPs) at cellular and tissue levels have not been fully understood, some of these biological effects might be employed in assisted reproduction to improve male fertility particularly by enhancing sperm cell quality either in vivo or in vitro. This review summarises the available literature regarding the potential applications of nanomaterials in farm animal reproduction, with a specific focus on the male gamete and on different strategies to improve breeding performances, transgenesis and targeted delivery of substances to a sperm cell. Antioxidant, antimicrobial properties and special surface binding ligand functionalization and their applications for sperm processing and cryopreservation have been reviewed. In addition, nanotoxicity and detrimental effects of NPs on sperm cells are also discussed due to the increasing concerns regarding the environmental impact of the expanding use of nanotechnologies on reproduction.

Superhydrophobic silica nanoparticles as ultrasound contrast agents

Microbubbles have been widely studied as ultrasound contrast agents for diagnosis and as drug/gene carriers for therapy. However, their size and stability (lifetime of 5-12min) limited their applications. The development of stable nanoscale ultrasound contrast agents would therefore benefit both. Generating bubbles persistently in situ would be one of the promising solutions to the problem of short lifetime. We hypothesized that bubbles could be generated in situ by providing stable air nuclei since it has been found that the interfacial nanobubbles on a hydrophobic surface have a much longer lifetime (orders of days). Mesoporous silica nanoparticles (MSNs) with large surface areas and different levels of hydrophobicity were prepared to test our hypothesis. It is clear that the superhydrophobic and porous nanoparticles exhibited a significant and strong contrast intensity compared with other nanoparticles. The bubbles generated from superhydrophobic nanoparticles sustained for at least 30min at a MI of 1.0, while lipid microbubble lasted for about 5min at the same settings. In summary MSNs have been transformed into reliable bubble precursors by making simple superhydrophobic modification, and made into a promising contrast agent with the potentials to serve as theranostic agents that are sensitive to ultrasound stimulation.

Cell penetrating peptide of sodium-iodide symporter effect on the I-131 radiotherapy on thyroid cancer

The aim of the present study was to clarify whether the cell penetrating peptide of sodium-iodide symporter (NIS) has an effect on the I-131 radiotherapy of thyroid cancer. Firstly, we combined the HIV-1 TAT peptide (a cell penetrating peptide, dTAT) and established a nanoparticle vector (dTAT NP) to study the delivery efficiency of this cell-penetrating strategy for tumor-targeted gene delivery. dTAT NP was transfected into cultured TPC-1 cells as a model to study the effects of I-131 radiotherapy on thyroid cancer. Reverse transcription-quantitative polymerase chain reaction and western blotting results showed that the mRNA and protein expression levels of NIS in the transfected TPC-1 cells were substantially higher than in the negative control cells. MTT and flow cytometric analyses demonstrated that the cell growth and apoptosis rates of the TPC-1 cells were significantly inhibited and activated, respectively, by treatment with dTAT NP. The results of DAPI staining showed that treatment with dTAT NP visibly increased the nuclear apoptosis rate of the TPC-1 cells. The effect of dTAT NP on TPC-1 cells was associated with the promotion of caspase-3 and downregulation of the PI3K/Akt signaling pathway. In summary, the present data provide a pre-clinical proof-of-concept for a novel gene delivery system that efficiently delivers NIS to the targeted cancer cells and presents a satisfactory efficacy. This approach may offer an effective strategy for improving thyroid cancer gene therapy.

Development of a laser-activated mesoporous silica nanocarrier delivery system for applications in molecular and genetic research

Nanoparticles have revolutionized medical research over the last decade. One notable emerging area of nanomedicine is research developments in the reproductive sciences. Since increasing evidence indicates links between abnormal gene expression and previously unexplained states of infertility, there is a strong impetus to develop tools, such as nanoparticle platforms, to elucidate the pathophysiological mechanisms underlying such states. Mesoporous silica nanoparticles (MSNPs) represent a powerful and safe delivery tool for molecular and genetic investigations. Nevertheless, ongoing progress is restricted by low efficiency and unpredictable control of cargo delivery. Here, we describe for the first time, the development of a laser-activated MSNP system with heat-responsive cargo. Data derived from human embryonic kidney cells (HEK293T) indicate that when driven by a heat-shock promoter, MSNP cargo exhibits a significantly increased expression following infrared laser stimulus to stimulate a heat-shock response, without adverse cytotoxic effects. This delivery platform, with increased efficiency and the ability to impart spatial and temporal control, is highly useful for molecular and genetic investigations. We envision that this straightforward stimuli-responsive system could play a significant role in developing efficient nanodevices for research applications, for example in reproductive medicine.

Potential toxicity of engineered nanoparticles in mammalian germ cells and developing embryos: treatment strategies and anticipated applications of nanoparticles in gene delivery

BACKGROUND

Engineered nanoparticles (ENPs) offer technological advantages for a variety of industrial and consumer products as well as show promise for biomedical applications. Recent progress in the field of nanotechnology has led to increased exposure to nanoparticles by humans. To date, little is known about the adverse effects of these ENPs on reproductive health, although interest in nanotechnology area is growing. A few biocompatible ENPs have a high loading capacity for exogenous substances, including drugs, DNA or proteins, and can selectively deliver molecular cargo into cells; however, they represent a potential tool for gene delivery into gametes and embryos.

OBJECTIVE AND RATIONALE

Understanding the reprotoxicological aspects of these ENPs is of the utmost importance to reliably estimate its potential impact on human health. In addition, a search for protective agents to combat ENP-mediated reproductive toxicity is warranted. Therefore, in this review we summarize the toxic effects of a few ENPs (metal and metal oxides, carbon-based nanoparticles, quantum dots and chitosan) in mammalian germ cells and developing embryos, and propose some treatment strategies that could mitigate nanoparticle-mediated toxicity. In addition, we outline the anticipated applications of ENPs in transgenic animal production in order to generate models for investigations into the mechanisms for human disease.

SEARCH METHODS

A literature search was performed using the National Center for Biotechnology Information PubMed database up until March 2016 and relevant keywords were used to obtain information regarding mammalian germ cell-specific toxicity and embryotoxicity of ENPs, possible treatment strategies, as well as the anticipated applications of nanoparticles in gene delivery in germ cells and embryos. Only English language publications were included.

OUTCOMES

Here, we demonstrate the toxicological effects of ENPs in mammalian germ cells and developing embryos by considering both in vitro and in vivo experimental models based on the existing literature. The biodistribution and cellular uptake of ENPs and the observed toxicities are mostly dependent on ENP size and surface-coating agents (surface functional groups/surface charge). ENPs have been shown to induce toxicity via oxidative stress, inflammation and DNA damage in both human and mouse germ cells. Use of antioxidant, anti-inflammatory drugs and selective metal chelators would be beneficial against nanoparticle-induced toxicity.

WIDER IMPLICATIONS

Our review provides the reproductive scientists a mechanistic insight into the reprotoxicological aspects of ENPs to reliably estimate its potential impact on human health and help to select/design protective agents to combat ENP-mediated toxicity. Furthermore, research regarding the detailed mechanism(s) of ENP toxicity in mammalian germ cells and developing embryos as well as the search for protective agents to combat ENP-mediated reproductive toxicity is warranted. Furthermore, we anticipate that investigations into the possibility of applying nanovectors to gene delivery in germ cells and early embryos will open new horizons in reproductive biology.

Mesoporous silica nanoparticles in tissue engineering – a perspective

In this review, we summarize the latest developments and give a perspective on future applications of mesoporous silica nanoparticles (MSNs) in regenerative medicine. MSNs constitute a flexible platform for controlled delivery of drugs and imaging agents in tissue engineering and stem cell therapy. We highlight the recent advances in applying MSNs for controlled drug delivery and stem cell tracking. We touch upon novel functions of MSNs in real time imaging of drug release and biological function, and as tools to control the chemical and mechanical environment of stem cells. We discuss the need for novel model systems for studying biofunctionality and biocompatibility of MSNs, and how the interdisciplinary activities within the field will advance biotechnology research.

Extracellular vesicle-mediated delivery of molecular compounds into gametes and embryos: learning from nature

BACKGROUND

Currently, even the most sophisticated methods of assisted reproductive technology (ART) allow us to achieve live births in only approximately 30% of patients, indicating that our understanding of the fine mechanisms underlying reproduction is far from ideal. One of the main challenges associated with studies of gamete structure and function is that these cells are remarkably resistant towards the uptake of exogenous substances, including 'molecular research tools' such as drugs, biomolecules and intracellular markers. This phenomenon can affect not only the performance of reproductive biology research techniques, but also the outcomes of the in vitro handling of gametes, which forms the cornerstone of ART. Improvement of intra-gamete delivery in a non-aggressive fashion is vital for the investigation of gamete physiology, and the advancement of infertility treatment. In this review, we outline the current state of nanomaterial-mediated delivery into gametes and embryos in vitro, and discuss the potential of a novel exciting drug delivery technology, based upon the use of targeted 'natural' nanoparticles known as extracellular vesicles (EVs), for reproductive science and ART, given the promising emerging data from other fields.

METHODS

A comprehensive electronic search of PubMed and Web of Science databases was performed using the following keywords: 'nanoparticles', 'nanomaterials', 'cell-penetrating peptides', 'sperm', 'oocyte', 'egg', 'embryo', 'exosomes', 'microvesicles', 'extracellular vesicles', 'delivery', 'reproduction', to identify the relevant research and review articles, published in English up to January 2015. The reference lists of identified publication were then scanned to extract additional relevant publications.

RESULTS

Biocompatible engineered nanomaterials with high loading capacity, stability and selective affinity represent a potential versatile tool for the minimally invasive internalization of molecular cargo into gametes and embryos. However, it is becoming increasingly clear that the translation of these experimental tools into clinical applications is likely to be limited by their non-biodegradable nature. To allow the subsequent use of these methodologies for clinical ART, studies should utilize biodegradable delivery platforms, which mimic natural mechanisms of molecular cargo trafficking as closely as possible. Currently, EVs represent the most physiological intracellular delivery tools for reproductive science and medicine. These natural mediators of cell communication combine the benefits of engineered nanomaterials, such as the potential for in vitro production, targeting and loading, with the essential feature of biodegradability.

CONCLUSION

We anticipate that future investigations into the possibility of applying EVs for the intentional intracellular delivery of molecular compounds into gametes and embryos will open new horizons for reproductive science and clinical ART, ultimately leading to improvements in patient care.

Nanomedicine and mammalian sperm: Lessons from the porcine model

Biomedical nanotechnology allows us to engineer versatile nanosized platforms that are comparable in size to biological molecules and intracellular organelles. These platforms can be loaded with large amounts of biological cargo, administered systemically and act at a distance, target specific cell populations, undergo intracellular internalization via endogenous uptake mechanisms, and act as contrast agents or release cargo for therapeutic purposes. Over recent years, nanomaterials have been increasingly viewed as favorable candidates for intragamete delivery. Particularly in the case of sperm, nanomaterial-based approaches have been shown to improve the efficacy of existing techniques such as sperm-mediated gene transfer, loading sperm with exogenous proteins, and tagging sperm for subsequent sex- or function-based sorting. In this short review, we provide an outline of the current state of nanotechnology for biomedical applications in reproductive biology and present highlights from a series of our studies evaluating the use of specialized silica nanoparticles in boar sperm as a potential delivery vehicle into mammalian gametes. The encouraging data obtained already from the porcine model in our laboratory have formed the basis for ethical approval of similar experiments in human sperm, thereby bringing us a step closer toward the potential use of this novel technology in the clinical environment.