He-Lin Xu

Thermo-sensitive hydrogels combined with decellularised matrix deliver bFGF for the functional recovery of rats after a spinal cord injury

Because of the short half-life, either systemic or local administration of bFGF shows significant drawbacks to spinal injury. In this study, an acellular spinal cord scaffold (ASC) was encapsulated in a thermo-sensitive hydrogel to overcome these limitations. The ASC was firstly prepared from the spinal cord of healthy rats and characterized by scanning electronic microscopy and immunohistochemical staining. bFGF could specifically complex with the ASC scaffold via electrostatic or receptor-mediated interactions. The bFGF-ASC complex was further encapsulated into a heparin modified poloxamer (HP) solution to prepare atemperature-sensitive hydrogel (bFGF-ASC-HP). bFGF release from the ASC-HP hydrogel was more slower than that from the bFGF-ASC complex alone. An in vitro cell survival study showed that the bFGF-ASC-HP hydrogel could more effectively promote the proliferation of PC12 cells than a bFGF solution, with an approximate 50% increase in the cell survival rate within 24 h (P < 0.05). Compared with the bFGF solution, bFGF-ASC-HP hydrogel displayed enhanced inhibition of glial scars and obviously improved the functional recovery of the SCI model rat through regeneration of nerve axons and the differentiation of the neural stem cells. In summary, an ASC-HP hydrogel might be a promising carrier to deliver bFGF to an injured spinal cord.

Glioma-targeted therapy using Cilengitide nanoparticles combined with UTMD enhanced delivery.

Malignant gliomas especially glioblastoma (GBM) are poorly responsive to the current treatments. Cilengitide (CGT) is a cyclic pentapeptide that demonstrated efficacy for GBM treatment by targeting the integrins avβ3 and avβ5 over-expressed on GBM cells. However, clinical translation of this therapy has been limited by issues including fast blood clearance, high kidney and liver uptake, poor blood-brain barrier (BBB) penetration, low tumor specificity and rapid washout from tumors. In this study, these issues were tackled in an integrated manner using a multi-stage strategy combining ultrasound-targeted microbubble destruction (UTMD) with CGT nanotherapy. CGT nanoparticles (CGT-NP) prepared using gelatin and Poloxamer 188-grafted heparin copolymer demonstrated significant apoptotic and cytotoxic effects in C6 GBM cells. Biodistribution study in a rat GBM model demonstrated buildup of high CGT level in tumors subjected to CGT-NP+UTMD combined therapy. The tumor CGT level in these animals was increased over 3-fold, tumor retention of CGT prolonged and renal clearance significantly reduced when compared with free CGT with or without UTMD. CGT-NP+UTMD treatment was further shown to extend the median survival period from less than 20days in the control and about 30days in free CGT group to about 80days. This was achieved with low CGT dosing level (2mg/kg twice weekly). In situ monitoring of GFAP, Ki67, caspase-3, Beclin-1, and LC-3 in the tumor samples together with TUNEL assay, transmission electron microscope imaging and Western blot assay all demonstrated high apoptotic and autophagy activities induced by the combined therapy. In conclusion, this study has provided extensive preclinical data supporting the use of this combined therapy to overcome the limitations of standard CGT treatment of gliomas.

Combination of coenzyme Q10-loaded liposomes with ultrasound targeted microbubbles destruction (UTMD) for early theranostics of diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common and lethal microvascular complications of diabetes. This study aimed to explore whether coenzymeQ10 (CoQ10) as an antioxidant combined with ultrasound-targeted microbubble destruction (UTMD) could reverse the progress of early diabetic nephropathy (DN). CoQ10 has great potential to treat early DN. However, the clinical application of CoQ10 has been limited because of its low aqueous solubility and non-specific distribution. Therefore, CoQ10-loaded liposomes (CoQ10-lip) were prepared and combined with ultrasound microbubbles for the early theranostics of DN. CoQ10-lip exhibited a good round morphology with a diameter of 183±1.7nm and a negative zeta potential of -25.3mV, which was capable of prolonging the release of the encapsulated CoQ10. The early DN rat models were induced by streptozotocin (STZ) and confirmed by contrast-enhanced ultrasound (CEUS) and 24-h urinary albumin. After the administration of CoQ10-lip combined with the UTMD technique to rats with early DN, the morphology and function of the kidney were evaluated by ultrasonography, histological and molecular analyses. The renal hemodynamics were significantly improved, moreover, 24-h urinary protein, and oxidative stress indexes were modulated after treatment with CoQ10-lip+UTMD indicating recovery of renal function. An elevated level of Nphs2 protein and reduced caspase 3 level indicated the preservation of podocytes and inhibition of cell apoptosis after CoQ10-lip+UTMD treatment. The molecular mechanism was associated with the upregulation of Bcl-2 and the downregulation of Bax. Moreover, the combination of CoQ10-lip and ultrasound microbubbles demonstrated a better protective effect on the damaged kidney than the other groups (free CoQ10 or CoQ10-lip+/- UTMD). Conclusively, CoQ10-lip in combination with ultrasound microbubbles might be a potential strategy to reverse the progress of early DN.

Three-dimensional structure micelles of heparin-poloxamer improve the therapeutic effect of 17β-estradiol on endometrial regeneration for intrauterine adhesions in a rat model

Intrauterine adhesions (IUA) frequently occur after infectious or mechanical injury to the endometrium, which may lead to infertility and/or pregnancy complications. There are few effective treatments due to the complex function of endometrium and shortage of native materials. 17β-estradiol (E2) is commonly used as an ancillary treatment in IUA patients, but it is limited by its poor solubility in aqueous solutions and low concentrations at the injured sites. In this research, a mini-endometrial curette was used to injure the rat’s endometrium to form an IUA model. 17β-estradiol was encapsulated into the micelles of heparin-poloxamer and a thermosensitive hydrogel (E2-HP hydrogel) was formed. This sustained releasing system was applied to restore the structure and function of the injured uterus. E2-HP hydrogel was constructed and relevant characteristics including gelation temperature and micromorphology were evaluated. Sustained release of 17β-estradiol from HP hydrogel was performed both in vitro and in vivo. Ultrasonography measurement and pathologic characteristics on the IUA rats were performed to evaluate the therapeutic effect of E2-HP hydrogel. Endoplasmic reticulum (ER) stress-related apoptosis was analyzed to explore the possible mechanisms in IUA recovery. E2-HP hydrogel showed a prolonged release of E2 at the targeting region and more effective endometrium regeneration in IUA rats. Significant improvements in both gland numbers and fibrosis area were observed in the E2-HP hydrogel group. We also demonstrated that E2-HP hydrogel in the recovery of IUA was closely related to the suppression of ER stress signals via the activation of downstream signals, PI3K/Akt and ERK1/2. HP hydrogel might be an effective approach to deliver E2 into the injured endometrium. Therapeutic strategies targeting ER stress using E2-HP hydrogel might be a promising solution for the treatment of women with intrauterine adhesions.

Skin-penetrating polymeric nanoparticles incorporated in silk fibroin hydrogel for topical delivery of curcumin to improve its therapeutic effect on psoriasis mouse model

A poor percutaneous penetration capability for most topical anti-inflammatory drugs is one of the main causes compromising their therapeutic effects on psoriatic skin. Even though curcumin has shown a remarkable efficacy in the treatment of psoriasis, its effective penetration through the stratum corneum is still a major challenge during transdermal delivery. The aim of our study was to design skin-permeating nanoparticles (NPs) to facilitate delivery of curcumin to the deeper layers of the skin. A novel amphiphilic polymer, RRR-α-tocopheryl succinate-grafted-ε-polylysine conjugate (VES-g-ε-PLL) was synthesized and self-assembled into polymeric nanoparticles. The nanoparticles of VES-g-ε-PLL exhibiting an ultra-small hydrodynamic diameter (24.4nm) and a positive Zeta potential (19.6mV) provided a strong skin-penetrating ability in vivo. Moreover, curcumin could effectively be encapsulated in the polymeric nanoparticles with a drug loading capacity of 3.49% and an encapsulating efficiency of 78.45%. In order to prolong the retention time of the ultra-small curcumin-loaded nanoparticles (CUR-NPs) in the skin, silk fibroin was used as a hydrogel-based matrix to further facilitate topical delivery of the model drug. In vitro studies showed that CUR-NPs incorporated in silk fibroin hydrogel (CUR-NPs-gel) exhibited a slower release profile of curcumin than the plain CUR-gel, without compromising the skin penetration ability of CUR-NPs. In vivo studies on miquimod-induced psoriatic mice showed that CUR-NPs-gel exhibited a higher therapeutic effect than CUR-NPs as the former demonstrated a more powerful skin-permeating capability and a more effective anti-keratinization process. CUR-NPs-gel was therefore able to inhibit the expression of inflammatory cytokines (TNF-α, NF-κB and IL-6) to a greater extent. In conclusion, the permeable nanoparticle-gel system may be a potential carrier for the topical delivery of lipophilic anti-psoriatic drugs.

Liposomes with Silk Fibroin Hydrogel Core to Stabilize bFGF and Promote the Wound Healing of Mice with Deep Second-Degree Scald

How to maintain the stability of basic fibroblast growth factor (bFGF) in wounds with massive wound fluids is important to accelerate wound healing. Here, a novel liposome with hydrogel core of silk fibroin (SF-LIP) is successfully developed by the common liposomal template, followed by gelation of liquid SF inside vesicle under sonication. SF-LIP is capable of encapsulating bFGF (SF-bFGF-LIP) with high efficiency, having a diameter of 99.8 ± 0.5 nm and zeta potential of -9.41 ± 0.10 mV. SF-LIP effectively improves the stability of bFGF in wound fluids. After 8 h of incubation with wound fluids at 37 °C, more than 50% of free bFGF are degraded, while only 18.6% of the encapsulated bFGF in SF-LIP are destroyed. Even after 3 d of preincubation with wound fluids, the cell proliferation activity and wound healing ability of SF-bFGF-LIP are still preserved but these are severely compromised for the conventional bFGF-liposome (bFGF-LIP). In vivo experiments reveal that SF-bFGF-LIP accelerates the wound closure of mice with deep second-degree scald. Moreover, due to the protective effect and enhanced penetration ability, SF-bFGF-LIP is very helpful to induce regeneration of vascular vessel in comparison with free bFGF or bFGF-LIP. The liposome with SF hydrogel core may be a potential carrier as growth factors for wound healing.

Implantable porous gelatin microspheres sustained release of bFGF and improved its neuroprotective effect on rats after spinal cord injury

In this study, porous gelatin microspheres (GMSs) were constructed to improve the neuroprotective effect of basic fibroblast growth factor (bFGF) on spinal cord injury. GMSs were prepared by a W/O emulsion template, followed by cross-linking, washing and drying. The particle sizes and surface porosity of the blank GMSs were carefully characterized by scan electronic microscopy. The blank GMSs have a mean particle size of 35μm and theirs surface was coarse and porous. bFGF was easily encapsulated inside the bulk GMSs through diffusion along the porous channel. 200μg of bFGF was completely encapsulated in 100mg of GMSs. The bFGF-loaded GMSs displayed a continuous drug release pattern without an obvious burst release over two weeks in vitro. Moreover, the therapeutic effects of bFGF-loaded GMSs were also evaluated in spinal cord injury rat model. After implantation of bFGF-loaded GMSs, the recovery of the motor function of SCI rats were evaluated by behavioral score and foot print experiment. The motor function of SCI rats treated with bFGF-loaded GMSs was more obvious than that treated with free bFGF solution (P<0.05). At the 28th days after treatment, rats were sacrificed and the injured spinal were removed for histopathological and apoptosis examination. Compared with treatment with free bFGF solution, treatment with bFGF-loaded GMSs resulted in a less necrosis, less infiltration of leukocytes, and a reduced the cavity ratio and less apoptotic cells in injured spinal(P<0.01), indicating its better therapeutic effect. Implantable porous GMSs may be a potential carrier to deliver bFGF for therapy of spinal cord injury.

A strategy for bypassing the blood-brain barrier: Facial intradermal brain-targeted delivery via the trigeminal nerve

ABSTRACT Although intranasal delivery bypasses the blood‐brain barrier (BBB), the anatomical location of the olfactory mucosa and respiratory airflow interference lead to less brain‐targeted drug delivery. In addition to intranasal delivery, evidence indicates that facial intradermal injection might be a novel strategy for bypassing the BBB via the trigeminal nerve (TN). The hypothesis was verified by pharmacokinetic evaluation, nasal injury, lymphatic vessels inhibition and immunohistochemistry. Intradermal injection into the rat mystacial pad (i.d.) elevated the brain sub‐areas and trigeminal Evans Blue (EB) concentrations, Cmax and AUC(0 − t). I.d. also increased them in brain sub‐areas beyond those of intranasal (i.n.) and intravenous injection (i.v.), especially the pons varolii and the medulla oblongata (sub‐areas associated with TN). I.d. injection increased the brain drug targeting efficiency, brain direct transport percentage and brain bioavailability of EB while i.n. injection altered them slightly. Trigeminal transection and nasal injury reduced trigeminal EB with i.d. administration. Trigeminal perineurium, epineurium, perivascular spaces, neurons and Schwann cells were involved in the EB brain‐targeted delivery. The lymphatic system mediated EB diffusion from the mystacial pad to the nasal mucosa and the brain. Thus, facial intradermal injection might be a promising strategy for brain‐targeting delivery, bypassing the BBB via the trigeminal substructures.

Temperature-sensitive heparin-modified poloxamer hydrogel with affinity to KGF facilitate the morphologic and functional recovery of the injured rat uterus

Abstract Endometrial injury usually results in intrauterine adhesion (IUA), which is an important cause of infertility and recurrent miscarriage in reproductive women. There is still lack of an effective therapeutic strategy to prevent occurrence of IUA. Keratinocyte growth factor (KGF) is a potent repair factor for epithelial tissues. Here, a temperature-sensitive heparin-modified poloxamer (HP) hydrogel with affinity to KGF (KGF-HP) was used as a support matrix to prevent IUA and deliver KGF. The rheology of KGF-HP hydrogel was carefully characterized. The cold KGF-HP solution was rapidly transited to hydrogel with suitable storage modulus (G′) and loss modulus (G″) for the applications of uterus cavity at temperature of 33 °C. In vitro release demonstrated that KGF was released from HP hydrogels in sustained release manner for a long time. In vivo bioluminescence imaging showed that KGF-HP hydrogel was able to prolong the retention of the encapsulated KGF in injured uterus of rat model. Moreover, the morphology and function of the injured uterus were significantly recovered after administration of KGF-HP hydrogel, which were evaluated by two-dimensional ultrasound imaging and receptive fertility. Not only proliferation of endometrial glandular epithelial cells and luminal epithelial cells but also angiogenesis of injured uterus were observed by Ki67 and CD31 staining after 7 d of treatment with KGF-HP hydrogel. Finally, a close relatively relationship between autophagy and proliferation of endometrial epithelial cells (EEC) and angiogenesis was firstly confirmed by detecting expression of LC3-II and P62 after KGF treatment. Overall, KGF-HP may be used as a promising candidate for IUA treatment.

Therapeutic supermolecular micelles of vitamin E succinate-grafted ε-polylysine as potential carriers for curcumin: Enhancing tumour penetration and improving therapeutic effect on glioma

Severe toxicity and poor tumour penetration are two intrinsic limited factors to hinder the broad clinical application for most of first-line chemotherapeutics. In this study, a novel vitamin E succinate-grafted ε-polylysine (VES-g-PLL) polymer was synthesized by using ε-polylysine as backbone. By adjusting VES graft ratio, VES-g-PLL (50) with a theoretic VES graft ratio of 50% could self-assemble into a supermolecular micelle with a hydrodynamic diameter (Dh) of ca.20nm, and Zeta potential of 19.6mV. VES-g-PLL micelles themselves displayed a strong anti-tumour effect on glioma. The poorly water-soluble curcumin was effectively encapsulated in VES-g-PLL micelles with the drug loading amount and entrapment efficiency reaching 4.32% and 82.27%, respectively. In a physiologic medium, curcumin-loaded VES-g-PLL micelles (Cur-Micelles) not only remained stable without obvious drug leakage but also sustained the release of its encapsulated curcumin for a long time. Because of the ultra-small size and positively-charged surface, Cur-Micelles penetrated the deeper tumour zone than free curcumin, resulting in a significant inhibition of tumour spheroids growth. Moreover, in vivo strong antitumor effect of Cur-Micelles was also exhibited at assistance of ultrasound-targeted microbubble destruction and the real-time MRI imaging demonstrated a nearly complete suppression of glioma after 28days of treatment. TUNEL staining showed that the therapeutic mechanism of Cur-Micelles was relevant to the apoptosis of tumour cells. Finally, in vivo nontoxicity of Cur-Micelles against normal organs including heart, liver, spleen, lung and kidney tissues was also demonstrated by the HE staining. In conclusion, VES-g-PLL micelles may serve as a potential carrier for curcumin to enhance tumour penetration and improve therapeutic effect on glioma.