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Objective. To prepare folic acid-chitosan conjugated nanoparticles (FA-CS NPs) and evaluate their targeting specificity on tumor cells. Methods. Chitosan (CS) NPs were prepared by ionic cross linking method, and folic acid (FA) was conjugated with CS NPs by electrostatic interaction. The properties of NPs were investigated, and doxorubicin hydrochloride (Dox) as a model drug was encapsulated for investigating drug release pattern in vitro. The cytotoxicity and cellular uptake of FA-CS NPs were also investigated. Results. The results reveal that the obtained FA-CS NPs were monodisperse nanoparticles with suitable average size and positive surface charge. Dox was easily loaded into FA-CS NPs, and the release pattern showed a long and biphasic drug release. Noticeable phagocytosis effect was observed in the presence of rhodamine B-labeled FA-CSNPs when incubating with the folate receptor-positive SMMC-7221 cells. Conclusion. Compared with the unmodified CS NPs, FA-CS NPs showed much higher cell uptaking ability due to the known folate-receptor mediated endocytosis. FA-CS NPs provide a potential way to enhance the using efficiency of antitumor drug by folate receptor mediated targeting delivery.

Hypertension is the most common cardiovascular disease. The discovery of the antihypertensive action of adenosine triphosphate-sensitive potassium (K(ATP)) channel openers was a significant advance in the treatment of hypertension. Iptakalim is a novel K(ATP) channel opener with a unique chemical structure that differs from other K(ATP) openers. Among the 3 different subtypes of K(ATP) channels heterologously expressed in human embryonic kidney cells and Xenopus oocytes, iptakalim exhibits significant selectivity for SUR2B/Kir6.1 channels, mild effects on SUR2A/Kir6.2 channels, and fails to open SUR1/Kir6.2 channels. Iptakalim is a more potent activator of the SUR2B/Kir6.1 subtype of K(ATP) channels than diazoxide and pinacidil, the 2 most commonly studied K(ATP) channel openers. Iptakalim selectively produces arteriolar vasodilation with essentially no effect on the capacitance vessels. It can preferentially relax arterioles and small arteries, without affecting large arteries. Furthermore, iptakalim strongly lowers the blood pressure of hypertensive rodents and humans but has little effect on normotensive rodents and humans. Selective antihypertensive action is not observed with pinacidil or diazoxide and may be due to the high selectivity of iptakalim for the SUR2B/Kir6.1 subtype of K(ATP) channels, as well as its selective relaxation of resistance vessels. In pulmonary arterial smooth muscle cells, iptakalim inhibits the increase of cytoplasmic free Ca2+ concentration, as well as cell proliferation induced by endothelin-1. Furthermore, iptakalim has exerted protective effects against hypertensive damage to target organs in rats and improves endothelial dysfunction associated with cardiovascular diseases by selective activation of the SUR2B/Kir6.1 subtype of K(ATP) channels expressed in the endothelium. Clinical trials of iptakalim in the treatment of mild-moderate hypertension have been completed in China. In additional to strong antihypertensive efficacy, iptakalim seems to have a favorable safety and tolerability profile. Iptakalim is a promising new generation antihypertensive drug.

We sought to explore new strategies targeting SUR2B/Kir6.1, a subtype of adenosine triphosphate (ATP)-sensitive potassium channels (KATP), against pressure overload-induced heart failure. The effects of natakalim, a SUR2B/Kir6.1 selective channel opener, on progression of cardiac remodeling were investigated. Pressure overload-induced heart failure was induced in Wistar rats by abdominal aortic banding. The effects of natakalim (1, 3, and 9 mg·kg⁻¹·d⁻¹ for 10 weeks) on myocardial hypertrophy and heart failure, cardiac histology, vasoactive compounds, and gene expression were assessed. Ten weeks after the onset of pressure overload, natakalim treatment potently inhibited cardiac hypertrophy and prevented heart failure. Natakalim remarkably inhibited the changes of left ventricular hemodynamic parameters and reversed the increase of heart mass index, left ventricular weight index, and lung weight index. Histological examination demonstrated that there was no significant hypertrophy or fibrosis in pressure-overloaded hearts of natakalim-treated rats. Ultrastructural examination of hearts revealed well-organized myofibrils with mitochondria grouped along the periphery of longitudinally oriented fibers in rats from the natakalim group. The content of serum nitric oxide and plasma prostacyclin was increased, whereas that of plasma endothelin-1 and cardiac tissue hydroxyproline and atrial and B-type natriuretic peptide messenger RNA was downregulated in natakalim-treated rats. Natakalim at 0.01-100 µM had no effects on isolated working hearts derived from Wistar rats; however, natakalim had endothelium-dependent vasodilatory effects on the isolated tail artery helical strips precontracted with norepinephrine. These results indicate that natakalim reduces heart failure caused by pressure overloading by activating the SUR2B/Kir6.1 KATP channel subtype and protecting against endothelial dysfunction.

Perinatal stem cells have been regarded as an attractive and available cell source for medical research and clinical trials in recent years. Multiple stem cell types have been identified in the human placenta. Recent advances in knowledge on placental stem cells have revealed that human amniotic epithelial stem cells (hAESCs) have obvious advantages and can be used as a novel potential cell source for cellular therapy and clinical application. hAESCs are known to possess stem-cell-like plasticity, immune-privilege, and paracrine properties. In addition, non-tumorigenicity and a lack of ethical concerns are two major advantages compared with embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). All of the characteristics mentioned above and other additional advantages, including easy accessibility and a non-invasive application procedure, make hAESCs a potential ideal cell type for use in both research and regenerative medicine in the near future. This review article summarizes current knowledge on the characteristics, therapeutic potential, clinical advances and future challenges of hAESCs in detail.