Alterations in the endometrium of rats, rabbits, and Macaca mulatta that received an implantation of copper/low-density polyethylene nanocomposite

Effective easing of the side effects of copper intrauterine devices using ultra-fine-grained Cu-0.4Mg alloy

Copper intrauterine device is one of the most adopted contraceptive methods with high effectiveness (over 99 %), low cost, spontaneous reversibility and long-lasting usage. However, the side effects induced from the initial burst release of copper ions (Cu²⁺) hinder the continuation of the Cu-IUD made of Coarse-Grained Copper (CG Cu). We proposed to tailor the bio-corrosion behaviors of better control of Cu²⁺ release via the addition of bioactive Mg into the Ultra-Fine Grained (UFG) Bulk Cu. Thus, UFG bulk Cu with 0.4 wt.% Mg was produced via equal-channel angular pressing. The microstructures of the UFG Cu-0.4Mg was observed using electron backscatter diffraction and transmission electron microscopy techniques. The in vitro long-term corrosion behaviors in simulated uterine fluid, cytotoxicity to four cell lines, in vivo biocompatibility and contraceptive efficacy were all studied on CG Cu, UFG Cu and UFG Cu-0.4Mg materials. The results demonstrate that both the ultrafine grains and the addition of bioactive Mg into Cu contribute to the suppression of the burst release of Cu²⁺ in the initial stage and the maintenance of high level Cu²⁺ in long-term release. Moreover, the UFG Cu-0.4Mg also exhibited much improved cell and tissue biocompatibility from both the in vitro and in vivo evaluations. Therefore, the contraceptive efficacy of UFG Cu-0.4Mg is still maintained as high as the CG Cu and UFG Cu while the side effects are significantly eased, suggesting the high potential of the UFG Cu-0.4Mg alloy as a new upgrading or alternative material for Cu-IUD. STATEMENT OF SIGNIFICANCE: The side effects from burst release of Cu²⁺ at the initial implantation stage of Cu-containing intrauterine devices (Cu-IUD) is one of the main drawbacks of these devices. In this work, an ultra-fine-grained Cu (UFG Cu) alloyed with a low amount of bioactive Mg was used for a Cu-IUD. The UFG Cu-0.4Mg alloy exhibited suppressed burst release of Cu²⁺ at initial implantation, while active Cu²⁺ release for long-term usage was maintained, comparable to coarse-grained pure Cu. Furthermore, the UFG Cu-0.4Mg alloy displayed significantly improved biocompatibility with human uterus cells and a much decreased inflammatory response within the uterus. Therefore, the side effects from Cu-IUD were eased, while high antifertility efficacy of the UFG Cu-0.4Mg alloy was maintained. The UFG Cu-0.4Mg alloy is promising for Cu-IUD.

Antifertility effectiveness of a novel polymer matrix composite and its influence on the endometrium in rhesus macaques (Macaca mulatta)

OBJECTIVE(S)

To explored the antifertility effectiveness and influence on the endometrium of a micro-copper/low-density polyethylene/methyl vinyl silicone rubber (Cu/LDPE/MVQ) composite in rhesus macaques.

STUDY DESIGN

Healthy reproductive aged female rhesus macaques underwent abdominal hysterotomy for surgical placement of either the experimental Cu/LDPE/MVQ composite (Cu/LDPE/MVQ, n=5), bare copper wire (Cu, n=5), or hysterotomy only sham-operation group [(SOI, n=4), (SOII, n=6)]. Females in the Cu/LPDE/MVQ, Cu, and SOI groups were housed with fertile males for approximately three menstrual cycles. We assessed pregnancy by hysterectomy. Females in the Cu/LDPE/MVQ, Cu, and SOII groups underwent hysterectomy at about 4 months post-insertion for histologic assessment of morphologic changes of the endometrium, evaluation of materials using scanning electron microscopy (SEM), and evaluation of the inflammatory markers, including substance P receptor (SPR), associated with endometrial bleeding using enzyme linked immunosorbent assay, quantitative RT-PCR, and Western blot analyses.

RESULTS

All of the SOI group females became pregnant (4/4, 100%). In contrast, no pregnancies occurred in either the Cu/LDPE/MVQ (0/5, 0%) or Cu (0/5, 0%) groups. We observed histologic features consistent with chronic endometrial inflammation in all females of the Cu group, but none of the SOII or Cu/LDPE/MVQ animals. Levels of inflammatory markers were significantly increased in the Cu group, compared with SOII or Cu/LDPE/MVQ groups (p<.05). SEM showed evidence of corrosion in the Cu wire not seen in the Cu/LDPE/MVQ group.

CONCLUSION(S)

Cu/LDPE/MVQ material provided a contraceptive effect similar to Cu in macaques, with a lower impact on inflammation and inflammatory markers of the endometrium.

IMPLICATIONS

This study demonstrates the possibility of a Cu/LDPE/MVQ composite as an alternative to conventional copper device materials.

Studies of acute and subchronic systemic toxicity associated with a copper/low-density polyethylene nanocomposite intrauterine device

Introduction

The physiologic safety of devices and materials intended for clinical implantation should be evaluated. This study, a logical extension of our previous work, aimed to investigate the safety of a novel contraceptive device, the copper/low-density polyethylene nanocomposite intrauterine device (nano-Cu/LDPE IUD), through studies of its potential toxicity after acute and subchronic administration in mice and rats.

Methods

For the acute toxicity study, single 50 mL/kg doses of nano-Cu/LDPE IUD extracts were administered to mice via intravenous or intraperitoneal injection. General behavioral adverse effects, mortality, and body weights were evaluated for up to 72 hours. In the 13-week subchronic toxicity study, the nano-Cu/LDPE composite with 10-fold higher than the standard clinical dose was implanted subcutaneously into the dorsal skin of Wistar rats. The control group underwent a sham procedure without material insertion.

Results

During all acute study observation times, the biologic reactions of the mice in the nano-Cu/LDPE group did not differ from those observed in the control group. The groups did not differ statistically in terms of body weight gain, and no macroscopic changes were observed in any organs. In the subchronic study, no clinical signs of toxicity or mortality were observed in either the nano-Cu/LDPE or control group during the 13-week period. The nano-Cu/LDPE composite did not cause any alterations in body weight, food consumption, hematologic and biochemical parameters, or organ weight relative to the control for any observed sample group. Histopathologic examinations of the organs revealed normal architecture, indicating that the inserted material did not cause morphologic disturbances in the rats.

Conclusion

Overall, the results indicate that the nano-Cu/LDPE IUD did not induce systemic toxicity under experimental conditions of the recommended standard practices, suggesting that the novel material IUD is safe and feasible for future contraceptive applications.

Effect of a novel copper-containing intrauterine device material on the endometrial environment in rabbits

OBJECTIVE(S)

This study aimed to determine whether intrauterine placement of a novel composite material [copper (Cu) microparticles, low-density polyethylene, and methyl vinyl silicone rubber (Cu/LDPE/MVQ)] could prevent pregnancy in rabbits, and to evaluate the effects of Cu/LDPE/MVQ on the endometrial environment.

STUDY DESIGN

Eighty sexually mature female rabbits were randomly divided into four groups (n=20 each group): control (sham-operated), LDPE/MVQ, Cu/LDPE/MVQ microcomposite, and bare Cu. Ten rabbits from each implant-bearing group were randomly selected for a mating experiment beginning 30 days after insertion. Pregnancy outcomes were observed 15 days after mating. Factors associated with endometrial bleeding and inflammation in the remaining rabbits in each group, and the surface conditions of the implants, were investigated 90 days post-insertion.

RESULTS

The Cu (0 embryo) and Cu/LDPE/MVQ (0 embryo) groups had significantly fewer embryos than the LDPE/MVQ (1.0±0.6 embryos, p<.05) and sham-operated groups (4.1±1.3 embryos, p<.05). Compared with bare Cu, the Cu/LDPE/MVQ composite material was associated with considerable reductions in injuries and factors associated with abnormal endometrial bleeding and inflammation, such as matrix metalloproteinase 9 (MMP9) and prostaglandin E2 (PGE₂). Additionally, the surface of implanted Cu/LDPE/MVQ remained much smoother than that of implanted bare Cu.

CONCLUSION(S)

This novel Cu-containing intrauterine device material exhibits a similar effect in prevention of pregnancy with bare copper, and lower levels of inflammatory markers.

IMPLICATIONS

This study demonstrates the potential of the novel Cu/LDPE/MVQ microcomposite material as a future substitute for conventional intrauterine device materials.

Copper nanoparticle-induced ovarian injury, follicular atresia, apoptosis, and gene expression alterations in female rats

Numerous studies have reported the accumulation of copper nanoparticles (Cu NPs) in organs and the corresponding damage, although whether Cu NPs can be translocated to the ovaries and their ovarian toxicity are still unknown. In this study, three groups of female rats were injected with 3.12, 6.25, or 12.5 mg/kg Cu NPs for 14 consecutive days. The pathological changes, hormone levels, apoptosis and apoptotic proteins, oxidative stress, and gene expression characteristics in the ovaries were then investigated. The results demonstrated that the Cu NPs exhibited obvious accumulation in the rat ovaries, leading to ovarian injury, an imbalance of sex hormones, and ovarian cell apoptosis. Cu NP exposure activated caspase 3, caspase 8, caspase 9, and tBid, decreased the protein levels of Bcl-2, increased the expression levels of the proteins Bax and cytochrome c, and promoted malondialdehyde (MDA) accumulation and superoxide dismutase (SOD) reduction. Furthermore, gene microarray analysis showed that Cu NPs (12.5 mg/kg/d) caused 321 differentially expressed genes. Of these, 180 and 141 genes were upregulated and downregulated, respectively. Hsd17b1, Hsd3b1, Hsd3b6, and Hsd3b were involved in steroid and hormone metabolism, whereas Mt3 and Cebpb were associated with apoptosis. Overall, these findings provide strong evidence that Cu NPs trigger both intrinsic and extrinsic apoptotic pathways and regulate key ovarian genes in oxidative stress-mediated ovarian dysfunction.