Cationic, anionic and neutral polysaccharides for skin tissue engineering and wound healing applications.

Today, chronic wound care and management can be regarded as a clinically critical issue. However, the limitations of current approaches for wound healing have encouraged researchers and physicians to develop more efficient alternative approaches. Advances in tissue engineering and regenerative medicine have resulted in the development of promising approaches that can accelerate wound healing and improve the skin regeneration rate and quality. The design and fabrication of scaffolds that can address the multifactorial nature of chronic wound occurrence and provide support for the healing process can be considered an important area requiring improvement. In this regard, polysaccharide-based scaffolds have distinctive properties such as biocompatibility, biodegradability, high water retention capacity and nontoxicity, making them ideal for wound healing applications. Their tunable structure and networked morphology could facilitate a number of functions, such as controlling their diffusion, maintaining wound moisture, absorbing a large amount of exudates and facilitating gas exchange. In this review, the wound healing process and the influential factors, structure and properties of carbohydrate polymers, physical and chemical crosslinking of polysaccharides, scaffold fabrication techniques, and the use of polysaccharide-based scaffolds in skin tissue engineering and wound healing applications are discussed.

The potential renal toxicity of silver nanoparticles after repeated oral exposure and its underlying mechanisms.

BACKGROUND: Silver nanoparticles (AgNPs) can accumulate in various organs after oral exposure. The main objective of the current study is to evaluate the renal toxicity induced by AgNPs after repeated oral exposure and to determine the relevant molecular mechanisms. METHODS: In this study, 40 male Wistar rats were treated with solutions containing 30, 125, 300, and 700 mg/kg of AgNPs. After 28 days of exposure, histopathological changes were assessed using hematoxylin-eosin (H&E), Masson's trichrome, and periodic acid-Schiff (PAS) staining. Apoptosis was quantified by TUNEL and immunohistochemistry of caspase-3, and the level of expression of the mRNAs of growth factors was determined using RT-PCR. RESULTS: Histopathologic examination revealed degenerative changes in the glomeruli, loss of tubular architecture, loss of brush border, and interrupted tubular basal laminae. These changes were more noticeable in groups treated with 30 and 125 mg/kg. The collagen intensity increased in the group treated with 30 mg/kg in both the cortex and the medulla. Apoptosis was much more evident in middle-dose groups (i.e., 125 and 300 mg/kg). The results of RT-PCR indicated that Bcl-2 and Bax mRNAs upregulated in the treated groups (p < 0.05). Moreover, the data related to EGF, TNF-α, and TGF-ß1 revealed that AgNPs induced significant changes in gene expression in the groups treated with 30 and 700 mg/kg compared to the control group. CONCLUSION: Our observations showed that AgNPs played a critical role in in vivo renal toxicity.

Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis.

Skin is the body's first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

Stem cell-based therapeutic strategies for corneal epithelium regeneration.

Any significant loss of vision or blindness caused by corneal damages is referred to as corneal blindness. Corneal blindness is the fourth most common cause of blindness worldwide, representing more than 5% of the total blind population. Currently, corneal transplantation is used to treat many corneal diseases. In some cases, implantation of artificial cornea (keratoprosthesis) is suggested after a patient has had a donor corneal transplant failure. The shortage of donors and the side effects of keratoprosthesis are limiting these approaches. Recently, researchers have been actively pursuing new approaches for corneal regeneration because of these limitations. Nowadays, tissue engineering of different corneal layers (epithelium, stroma, endothelium, or full thickness tissue) is a promising approach that has attracted a great deal of interest from researchers and focuses on regenerative strategies using different cell sources and biomaterials. Various sources of corneal and non-corneal stem cells have shown significant advantages for corneal epithelium regeneration applications. Pluripotent stem cells (embryonic stem cells and iPS cells), epithelial stem cells (derived from oral mucus, amniotic membrane, epidermis and hair follicle), mesenchymal stem cells (bone marrow, adipose-derived, amniotic membrane, placenta, umbilical cord), and neural crest origin stem cells (dental pulp stem cells) are the most promising sources in this regard. These cells could also be used in combination with natural or synthetic scaffolds to improve the efficacy of the therapeutic approach. As the ocular surface is exposed to external damage, the number of studies on regeneration of the corneal epithelium is rising. In this paper, we reviewed the stem cell-based strategies for corneal epithelium regeneration.

Mesenchymal Stem Cells Ameliorate Cuprizone-Induced Demyelination by Targeting Oxidative Stress and Mitochondrial Dysfunction.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. The main causes of MS disease progression, demyelination, and tissue damage are oxidative stress and mitochondrial dysfunction. Hence, the latter are considered as important therapeutic targets. Recent studies have demonstrated that mesenchymal stem cells (MSCs) possess antioxidative properties and are able to target mitochondrial dysfunction. Therefore, we investigated the effect of transplanting Wharton's jelly-derived MSCs in a demyelination mouse model of MS in which mice were fed cuprizone (CPZ) for 12 weeks. CPZ is a copper chelator that impairs the activity of cytochrome oxidase, decreases oxidative phosphorylation, and produces degenerative changes in oligodendrocytes, leading to toxic demyelination similar to those found in MS patients. Results showed that MSCs caused a significant increase in the percentage of myelinated areas and in the number of myelinated fibers in the corpus callosum of the CPZ + MSC group, compared to the CPZ group, as assessed by Luxol fast blue staining and transmission electron microscopy. In addition, transplantation of MSCs significantly increased the number of oligodendrocytes while decreasing astrogliosis and microgliosis in the corpus callosum of the CPZ + MSC group, evaluated by immunofluorescence. Moreover, the mechanism by which MSCs exert these physiological effects was found to be through abolishing the effect of CPZ on oxidative stress markers and mitochondrial dysfunction. Indeed, malondialdehyde significantly decreased while glutathione and superoxide dismutase significantly increased in CPZ + MSC mice group, in comparison witth the CPZ group alone. Furthermore, cell therapy with MSC transplantation increased the expression levels of mitochondrial biogenesis transcripts PGC1α, NRF1, MFN2, and TFAM. In summary, these results demonstrate that MSCs may attenuate MS by promoting an antioxidant response, reducing oxidative stress, and improving mitochondrial homeostasis.

Biopolymer-based scaffolds for corneal stromal regeneration: A review.

The stroma is one of the 5 layers of the cornea that comprises more than 90% of the corneal thickness, and is the most important layer for the transparency of cornea and refractive function critical for vision. Any significant damage to this layer may lead to corneal blindness. Corneal blindness refers to loss of vision or blindness caused by corneal diseases or damage, which is the 4th most common cause of blindness worldwide. Different approaches are used to treat these patients. Severe corneal damage is traditionally treated by transplantation of a donor cornea or implantation of an artificial cornea. Other alternative approaches, such as cell/stem cell therapy, drug/gene delivery and tissue engineering, are currently promising in the regeneration of damaged cornea. The aim of tissue engineering is to functionally repair and regenerate damaged cornea using scaffolds with or without cells and growth factors. Among the different types of scaffolds, polymer-based scaffolds have shown great potential for corneal stromal regeneration. In this paper, the most recent findings of corneal stromal tissue engineering are reviewed.

Effects of adipose- derived stromal vascular fraction on asherman syndrome model.

Asherman's syndrome (AS) is an endometrial damage that results in infertility in women. Although stem cell therapy has been introduced as a potential treatment for this syndrome, its use in clinical settings remains challenging because of the likelihood of contamination and cell differentiation. Herein, we investigated the effects of adipose-derived stromal vascular fraction (SVF) transplantation on proliferation and angiogenesis in the endometrium in an AS model. The AS model was induced using scratch method in adult male Wistar rats, and SVF (5 × 10 (Simsir et al., 2019) cells) was locally administered into the damaged horns. Two weeks after cell transplantation, endometrial thickness, fibrosis, and expression of vascular endothelial growth factor (VEGF) were assessed by Hematoxylin & Eosin, Masson's trichrome, and immunofluorescence staining, respectively. We found thin endometrium, increased fibrosis, and decreased VEGF following AS induction all of which were reversed after SVF transplantation. We concluded that the local injection of SVF may serve as an effective alternative therapy for AS.

Comparison of the regenerative effects of bone marrow/adipose-derived stem cells in the Asherman model following local or systemic administration.

PURPOSE: Cell therapy is a promising strategy for the treatment of Asherman's syndrome (AS), but the origin of these cells and injection route influence the therapeutic effect and complications of cell therapy. Herein, we compared the effects of systemic or local intrauterine injection of bone marrow or adipose-derived mesenchymal stem cells (BMSCs/AMSCs) on the endometrium in a rat model of AS. METHODS: After induction of AS in adult Wistar rats, the CM-Dil-positive BMSCs or AMSCs were injected either locally or intravenously. After 3 weeks, endometrial thickness, collagen deposition, cell migration, and VEGF expression were evaluated using histochemistry/immunofluorescence studies. RESULTS: In all stem cell-treated groups, an ameliorative effect on the damaged endometrium was noted. Collagen deposition diminished in both groups (IV and local injection) compared to the AS model. In rats injected locally with MSC, fibrosis decreased compared to the other groups. Moreover, endometrial thickness increased in the groups that received local injection of BMSCs and AMSCs more than the IV-transplanted AMSCs group. Immunofluorescent staining demonstrated that although the systemic transplantation of BMSCs was more effective than the other groups on VEGF expression, it led to the lowest number of CM-Dil+ stem cells in the damaged endometrium. CONCLUSION: Stem cell transplantation may reconstruct the damaged endometrium, but it is recommended to select the most effective stem cells and injection route. Because the removal of the fibrosis and the replacement of the epithelia cells is an effective therapeutic strategy for AS, in this study, we conclude that the local injection of AMSCs is more appropriate than BMSCs to treat AS.

Resveratrol supplementation improves DNA integrity and sperm parameters in streptozotocin-nicotinamide-induced type 2 diabetic rats.

Reproductive dysfunction is one of the diabetes complications. Resveratrol, a polyphenol compound, shows antidiabetic and antioxidant effects. The aim of the present study was to investigate the protective effects of resveratrol on sperm parameters and chromatin quality in experimentally induced type 2 diabetes by streptozotocin and nicotinamide. Forty male adult Wistar rats were grouped into normal control, diabetic control and resveratrol-treated diabetic groups (1, 5 and 10 mg/kg orally treated for 30 days). Type 2 diabetes was induced using a single dose of streptozotocin and nicotinamide by intraperitoneal injection. Then, the different parameters and chromatin condensation of the epididymal extracted spermatozoon were studied using aniline blue (AB), acridine orange (AO) and toluidine blue (TB) staining. The sperm parameters including count, motility and viability had significant reduction in diabetic rats (p < 0.05). Resveratrol increased count, motility and viable spermatozoa relative to the diabetic group (p < 0.05). The mean percentage of AB, AO and TB staining positive spermatozoa was increased in diabetic groups compared to control (p < 0.001) and decreased after treatment with 1 and 5 mg/kg resveratrol (p < 0.001). The results of AO and TB staining showed that resveratrol did not have any beneficial effect on chromatin condensation and denatured DNA at the dose of 10 mg/kg.

The effect of silver nanoparticles on the reproductive system of adult male rats: A morphological, histological and DNA integrity study.

BACKGROUND: Silver nanoparticles (AgNPs) are more often used in various products, and consequently the potential deleterious effects associated with exposure to them are of concern. Several lines of evidence have demonstrated that the toxicity of AgNPs affects different organs and leads to some side effects, including weight loss, inflammation and cell death. OBJECTIVES: The aim of this study was to evaluate the effect of different concentrations of AgNPs on sperm parameters and testicular histology. MATERIAL AND METHODS: In the present study, 28 male adult Wistar rats were categorized into a control group and 3 experimental groups (AgNP-1, AgNP-2 and AgNP-3), intraperitoneally (i.p.) receiving 30, 125 and 300 mg/kg of AgNPs, respectively. Twenty-eight days after injection the epididymes and the testes of each rat were dissected in order to evaluate sperm parameters, sperm chromatin integrity and histomorphometric changes in the testicular tissue. RESULTS: The results showed a significant decrease in sperm count (p < 0.0001), vitality (p < 0.05) and morphology changes (p < 0.001) in the group receiving 300 mg/kg of AgNPs compared to the control group. A significant decrease was also observed in the number of spermatogonia, Sertoli and Leydig cells in the AgNP-2 and AgNP-3 groups (p < 0.05). The evaluation of sperm chromatin did not show any significant differences among the experimental groups (p > 0.05). CONCLUSIONS: The data showed some dose-dependent adverse effects of AgNPs on sperm and seminiferous tubules. More experimental investigations are necessary to draw better conclusions regarding the safety of nanoparticles (NPs) on the male reproduction system.

Sublethal concentration of H2O2 enhances the protective effect of mesenchymal stem cells in rat model of spinal cord injury.

OBJECTIVE: To investigate the effect of H2O2 on the migration and antioxidant defense of mesenchymal stem cells (MSCs) and the neurotrophic effects of H2O2-treated MSCs on spinal cord injury (SCI). RESULTS: Sublethal concentrations of H2O2 decreased cell migration and expression of CXCR4 and CCR2 as well as Nrf2 expression in MSCs. In the second phase, transplantation of treated and untreated MSCs to SCI caused minor changes in locomotor dysfunction. There was a significantly difference between cell-treated and spinal cord injury groups in expression of BDNF (brain-derived neurotrophic factor). Transplantation of H2O2-treated cells caused an increase in BDNF expression compared to non-treated cells. CONCLUSION: Transplantation of H2O2-treated stem cells may have protective effects against SCI through by increasing neurotrophic factors.

Effect of Antioxidants on Testicular iNOS and eNOS after High-Fat Diet in Rat.

BACKGROUND AND OBJECTIVE: Spermatogenesis is a process by which germ cells produce spermatozoa and can be disturbed at every level. Nitric Oxide Synthases (NOS), implicate in interactions with Oxidative Stress (OS) which is one of the main factors in the etiology of male infertility. The High Fat Diet (HFD) is a major factor of obesity which in turn is important for enhancing OS. Antioxidants and garlic could attenuate or reverse effects of HFD. The aim of the study was to investigate the effects of dietary antioxidants and garlic on testicular inducible NOS (iNOS) and endothelial NOS (eNOS) in Wistar albino rats fed on HFD. MATERIALS AND METHODS: Groups (each n = 8) were: SD (100% access to standard diet), F-HFD, (100% access to HFD) and R-HFD (70% access to HFD), F-HFD +antioxidants, F-HFD+garlic and R-HFD+antioxidants. The HFD consisted of a 60% fatty diet in 3 forms: Without antioxidants, with antioxidants and with garlic. The testicular iNOS and eNOS were studied by immunohistochemical (IHC) method. Also used ANOVA, repeated measures ANOVA, t-tests and Tukey's test (where necessary) to analyze the data (p<0.05). RESULTS: The iNOS increased in the F-HFD and R-HFD+antioxidants groups. The eNOS increased in R-HFD,F-HFD and F-HFD+garlic groups. The H-E evaluation in R-HFD group showed a decrease in spermatogenesis score count and seminiferous tubules diameters (µm) in comparison with the SD and F-HFD groups. R-HFD+antioxidants group had lower score than F-HFD+antioxidants and F-HFD+garlic groups. CONCLUSION: Restricted fat diet consumption causes increase in weight and impairs spermatogenesis. Results of this study reveal that adding the antioxidants can't improve histological changes of testis. The iNOS expression in seminiferous tubules in restricted fat diet along with antioxidants, suggest a potential role of iNOS in spermatogenesis and male infertility.

Dietary supplementation with astaxanthin may ameliorate sperm parameters and DNA integrity in streptozotocin-induced diabetic rats.

OBJECTIVE: Diabetes mellitus (DM) is known to cause many systemic complications as well as male infertility. Astaxanthin (ASTX) is a powerful antioxidant that is involved in a variety of biologically active processes, including those with anti-diabetes effects. The present study investigates the effect of ASTX on the spermatozoa function in streptozotocin (STZ)-induced diabetic rats. METHODS: We divided 30 adult rats into three groups (10 rats per group), with a control group that received corn oil mixed with chow. DM was induced by intra-peritoneal injection of STZ. Eight weeks after the STZ injection, half of the diabetic animals were used as diabetic controls, and the rest were treated with ASTX for 56 days. Then the parameters and chromatin integrity of the epididymal sperm were analyzed using chromomycin A3, toluidine blue (TB), and acridine orange (AO) staining. RESULTS: The count, viability, and motility of the epididymal sperm were decreased significantly in the STZ group in comparison with the control group (count and viability, p<0.001; motility, p<0.001;0.01). ASTX increased normal morphology and viable spermatozoa compared to the STZ group (morphology, p=0.001; viability, p<0.001;0.05). The percentage of abnormal chromatins in TB and AO staining was higher in the STZ group compared to the control group (p<0.001;0.001). The mean percentage of TB and AO positive spermatozoa in STZ rats was significantly lower in the STZ+ASTX group (TB, p=0.001; AO, p<0.001;0.05). CONCLUSION: This study observed that in vivo ASTX treatment partially attenuates some detrimental effect of diabetes. Conversely, ASTX improved sperm viability, normal morphology, and DNA integrity.

Effect of a high fat diet on ovary morphology, in vitro development, in vitro fertilisation rate and oocyte quality in mice.

INTRODUCTION: The aim of this study was to determine the effect of a high-fat diet (HFD) on oocyte maturation and quality in a mouse model. METHODS: Female BALB/c mice were allocated to one of the following groups: (a) control group (n = 40), which received a controlled diet; or (b) HFD group (n = 40), which received an HFD for 12 weeks. Sections of the ovary were examined histologically. The number of follicles and corpora lutea were counted. In vitro maturation and in vitro fertilisation (IVF) were assessed in germinal vesicle (GV) and metaphase II (MII) oocytes, respectively. The expression of bone morphogenetic protein 15 (BMP15) and leptin receptor genes in GV and MII oocytes was evaluated using reverse transcription real-time polymerase chain reactions. RESULTS: In the HFD group, there was a decreased number of primordial and Graafian follicles, as well as corpora lutea (p < 0.05). The rate of oocyte development to the MII stage was also reduced (p < 0.001). Cumulus expansion was observed more frequently in the control group than the HFD group (p < 0.05). The IVF rate in the HFD group was lower than that in the control group (p < 0.05). In the HFD group, BMP15 and leptin receptor genes were upregulated in the GV stage (p > 0.05) and MII stage (p < 0.05), compared to the control group. CONCLUSION: An HFD reduces folliculogenesis in the primordial and Graafian stages, in vitro maturation and in vitro fertilisation rates, as well as oocyte quality in mice.

Protective Effects of Antioxidants on Sperm Parameters and Seminiferous Tubules Epithelium in High Fat-fed Rats.

BACKGROUND: Prescription of antioxidants might increase the quality of sperm parameters and improve the rate of pregnancy in obese people who suffer from infertility. Therefore, the present study investigated protective effects of vitamin A, E and astaxanthin on sperm parameters and seminiferous tubules epithelium in high-fat diet model. METHODS: Thirty-six numbers of 3 months old albino Wistar rats were divided to control, high-fat diet and high-fat diet with antioxidants groups. After 12 weeks, levels of LDL-C and HDL-C were detected in the groups. Sperm was obtained from the tail of epididymis and its parameters (count, vitality, motility and morphology) were analyzed. Testes were fixed in 10% formalin and after tissue processing, stained with Hematoxylin and Eosine (H&E) for histological evaluation. Data were analyzed by a one-way ANOVA and p < 0.05 was considered significant. RESULTS: Our results indicated that viability, motility and normal morphology of sperm in high-fat diet (HFD) decreased significantly compared to high-fat diet with antioxidant (HFD + A) and the control groups (p < 0.05). Also spermatogonium and the number of Sertoli cells increased significantly in HFD + A compared to the control (p < 0.05). CONCLUSION: As it is shown in our study, application of antioxidants decreased serum triglyceride, cholesterol and HDL-C/LDL-C in high-fat diet model and improved the semen parameters. Therefore, it is suggested that the low quality of sperm can be improved in obese men through antioxidant prescription. Finally, it seems that the antioxidants in obese patients with subfertility or infertility is a new and efficient strategy with few side effects.

Effect of myomectomy on endometrial glutathione peroxidase 3 (GPx3) and glycodelin mRNA expression at the time of the implantation window.

BACKGROUND: In fertile women, glycodelin and glutathione peroxidase 3 (GPx3) genes expression rises during the luteal phase, with a peak occurring during the implantation window. The expression of these genes decreases in women with myomas. To determine whether myomectomy would reverse glycodelin and GPx3 expression, we evaluated the transcript levels of these genes in the endometrium of patients before and after myomectomy. METHODS: Expression of glycodelin and GPx3 genes were examined prospectively during the midluteal phase in the endometrium obtained from infertile women with myoma (n = 12) before and three months after myomectomy. Endometrial expression of these genes was evaluated using quantitative real-time RT-PCR. RESULTS: Endometrial glycodelin mRNA expression levels (normalized to 18S rRNA expression) were increased significantly in endometrium of patients after myomectomy (P = 0.02). GPx3 mRNA expression was increased insignificantly after myomectomy (P = 0.43). CONCLUSION: The results showed that myomectomy increased endometrial glycodelin (significantly) and GPx3 (not significantly) gene expression after 3 months. Study at different times and detecting expression of these genes can reveal more details.

Effect of intramural myomectomy on endometrial HOXA10 and HOXA11 mRNA expression at the time of implantation window.

BACKGROUND: HOXA11 and HOXA10 are expressed in endometrium throughout the menstrual cycle and show a dramatic increase during the mid-luteal phase at the time of implantation. The expression of these genes is decreased in women with myomas. OBJECTIVE: To determine whether myomectomy would reverse HOXA11 and HOXA10 expression, we evaluated the transcript levels of these genes in the endometria of patients before and after myomectomy. MATERIALS AND METHODS: Expression of HOXA11 and HOXA10 were examined prospectively during the midluteal phase in endometrium obtained from infertile women (n=12) with myoma before and three months after myomectomy. Endometrial HOXA11 and HOXA10 expression were evaluated using quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Endometrial HOXA11 and HOXA10 mRNAs expression levels (normalized to 18SrRNA) were increased insignificantly in endometrium of patients after myomectomy (p=0.7 and p=0.15 respectively). CONCLUSION: The results suggest that the alteration in expression pattern of these genes could not account for some aspects of fertility after myomectomy. This article extracted from M.Sc. thesis. (Shamila Faramarzi).

Semi-quantitative analysis of HOXA11, leukemia inhibitory factor and basic transcriptional element binding protein 1 mRNA expression in the mid-secretory endometrium of patients with endometriosis.

BACKGROUND: HOXA11 and leukemia inhibitory factor (LIF) and basic transcriptional element binding protein1 (BTEB1) are expressed in endometrium throughout the menstrual cycle and show a dramatic increase during the mid-luteal phase at the time of implantation. In this case-control study, the expression pattern of these mRNA was evaluated in patients with endometriosis at the time of implantation. We also describe a semi-quantitative RT-PCR protocol optimized in our laboratory. METHODS: Eight patients with endometriosis were considered as our case and 8 fertile women as control group. Expression levels of HOXA11, LIF and BTEB1 mRNA were measured in endometrium during the mid-secretory phase using semi-quantitative RT-PCR. RESULTS: We describe the detailed procedure for the analysis of HOXA11, LIF and BTEB1 mRNA levels. Endometrial HOXA11 and LIF mRNA expression levels (normalized to beta-actin expression) were significantly decreased in endometrium of infertile patients with endometriosis compared with healthy fertile controls at the time of implantation (P < 0.05). A similar trend was seen in BTEB1 mRNA expression. CONCLUSION: The results suggest that the alteration in expression pattern of the some genes could account for some aspects of infertility in endometriosis.

Degradation of maternal mRNA in mouse embryos: selective degradation of specific mRNAs after fertilization.

During oogenesis, mRNA is actively transcribed and accumulated in growing oocytes, but this transcription stops before the oocytes grow to their full size. The accumulated maternal mRNA is used for protein synthesis in the oocytes during meiotic maturation and even in the embryos to sustain development after fertilization. Therefore, the degradation of accumulated maternal mRNA starts during meiotic maturation, but its rate is slow. Nevertheless, some mRNA species should rapidly degrade after fertilization if they encode proteins that play a role in specific events during meiosis and are detrimental for development after fertilization. In this study, to identify the selective degradation of maternal transcripts after fertilization, we sought mRNAs that are degraded in the early hours after fertilization by constructing an oocyte cDNA library after subtracting the cDNA of embryos at the mid one-cell stage. H1oo, c-mos, tPA (tissue type plasminogen activator gene), and Gdf9 were identified as genes whose transcripts undergo rapid degradation after fertilization. RT-PCR analysis showed that none of these transcripts was expressed during pre-implantation development once they were eliminated, suggesting that the mRNA species that are required for oogenesis, but not for early pre-implantation development, are degraded rapidly after fertilization. Microinjection of chimeric mRNAs in which the coding and 3'-untranslated regions (3'UTR) were exchanged between c-mos and hypoxanthine phosphoribosyltransferase mRNAs revealed that the 3'UTR plays a role in the rapid degradation that occurs after fertilization. Cytoplasmic polyadenylation elements (CPEs) was found near a poly(A) signal in the 3'UTR of all the mRNA species identified as rapidly degrading mRNA. The mechanism for the selective degradation is discussed, in relation to its biological significance.