Placenta-anchored tadalafil liposomes rescues intrauterine growth restriction through continuous placental blood perfusion improvement

Physiological or pathological hypoperfusion of the placenta is one of the main causes of intrauterine growth restriction (IUGR) which poses a significant risk to the health of the fetus and newborn. Tadalafil, a 5-type phosphodiesterase inhibitor, has previously been found to improve the symptoms of IUGR in various clinical studies. Unfortunately, its clinical utility is hindered by its limited water solubility, rapid metabolism, and lack of specific distribution in target tissues rendering tadalafil unable to maintain long-term placental perfusion. In this study, iRGD-modified tadalafil-loaded liposomes (iRGD-lipo@Tad) featuring a size of approximately 480 nm were designed to rectify the shortcomings of tadalafil. The prepared iRGD-lipo@Tad exhibited superior stability, sustained drug release capacity, and low cytotoxicity. The fluorescence study, tissue slice study, and drug biodistribution study together demonstrated the placenta-anchored ability of iRGD-modified liposomes. This was achieved by a dual approach consisting of the iRGD-mediated placenta-targeting effect and special particle size-mediated placenta resident effect. The pharmacokinetic study revealed a significant improvement in the in vivo process of tadalafil encapsulated by the iRGD-modified liposomes. In comparison to the tadalafil solution, the peak plasma concentration of iRGD-lipo@Tad was significantly increased, and the area under the curve was increased by about 7.88 times. In the pharmacodynamic study, iRGD-lipo@Tad achieved a continuous and efficient improvement of placental blood perfusion. This was achieved by decreasing the ratio of plasma soluble fms-like tyrosine kinase to placental growth factor and increasing the levels of cyclic guanosine monophosphate and nitric oxide. Consequently, iRGD-lipo@Tad resulted in a significant increase in embryo weight and a reduction in the miscarriage rate of N-Nitro-L-arginine methyl ester-induced IUGR pregnant mice without detectable toxicity. In summary, the nanotechnology-assisted therapy strategy presented here not only overcomes the limitations of tadalafil in the clinical treatment of IUGR but also offers new avenues to address the treatment of other placenta-originated diseases.

Low recurrence rate of anchored conjunctival rotation flap technique in pterygium surgery

Background

To report the recurrence rate for an anchored conjunctival rotation flap technique in primary pterygium surgery.

Methods

Primary pterygium surgeries performed using anchored conjunctival rotation flap techniques (110 eyes in 110 patients) with a minimum follow-up of 12 months were reviewed. In this technique, a conjunctival flap is rotated to cover the bare sclera and suture-fixated with either 8–0 polyglactin (41 eyes) or 10–0 nylon (69 eyes). The recurrence rate was determined, and the two suture materials utilized were compared.

Results

The recurrence rate was 2.71% (3 cases in 110 eyes) when an anchored conjunctival rotation flap technique was used and patients were monitored for 26.40 ± 17.09 months. Interestingly, the recurrences were only observed in polyglactin-sutured eyes. No recurrence was detected in nylon-sutured eyes. No other complications were observed in either group.

Conclusions

The anchored conjunctival rotation flap technique for pterygium surgery has a relatively low recurrence rate. Nylon suture-fixation of the flap was found to be superior to polyglactin suture-fixation in preventing recurrence.

Electronic supplementary material

The online version of this article (10.1186/s12886-017-0587-z) contains supplementary material, which is available to authorized users.