Mesenchymal stem cells attenuated PLGA-induced inflammatory responses by inhibiting host DC maturation and function.

The poly lactic-co-glycolic acid (PLGA) bio-scaffold is a biodegradable scaffold commonly used for tissue repair. However, implanted PLGA scaffolds usually cause serious inflammatory responses around grafts. To improve PLGA scaffold-based tissue repair, it is important to control the PLGA-mediated inflammatory responses. Recent evidence indicated that PLGA induce dendritic cell (DC) maturation in vitro, which may initiate host immune responses. In the present study, we explored the modulatory effects of mesenchymal stem cells (MSC) on PLGA-induced DCs (PLGA-DC). We found that mouse MSCs inhibited PLGA-DC dendrite formation, as well as co-stimulatory molecule and pro-inflammatory factor expression. Functionally, MSC-educated PLGA-DCs promoted Th2 and regulatory T cell differentiation but suppressed Th1 and Th17 cell differentiation. Mechanistically, we determined that PLGA elicited DC maturation via inducing phosphorylation of p38/MAPK and ERK/MAPK pathway proteins in DCs. Moreover, MSCs suppressed PLGA-DCs by partially inactivating those pathways. Most importantly, we found that the MSCs were capable of suppressing DC maturation and immune function in vivo. Also, the proportion of mature DCs in the mice that received MSC-PLGA constructs greatly decreased compared with that of their PLGA-film implantation counterparts. Additionally, MSCs co-delivery increased regulatory T and Th2 cells but decreased the Th1 and Th17 cell numbers in the host spleens. Histological analysis showed that MSCs alleviated the inflammatory responses around the grafted PLGA scaffolds. In summary, our findings reveal a novel function for MSCs in suppressing PLGA-induced host inflammatory response and suggest that DCs are a new cellular target in improving PLGA scaffold-based tissue repair.

Effect of poly(DL-lactide-co-glycolide) on scar formation after glaucoma filtration surgery.

BACKGROUND: Glaucoma filtering surgery (GFS) is the most common procedure performed in the treatment of glaucoma. Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes, they may be associated with an increased incidence of severe and potentially blinding complications. Poly(DL-lactide-co-glycolide) (PDLLA/GA) is a bioresorbable polymer, which can be prepared with a large range of physical, mechanical, and biological properties and has been widely used in medicine, including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering. This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery (GFS). METHODS: Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each. PDLLA/GA membranes were put under the sclera flap for evaluation. GFS with no membrane inserted served as control. Clinical evaluations of intraocular pressure (IOP) and the presence of a filtration bleb were performed at intervals (3 days, 1, 2, 4, 8, 12, 20, and 24 weeks) postoperatively. At each time point, three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type IV, proliferating cell nuclear antigen (PCNA), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1). The expression of connective tissue growth factor (CTGF) mRNA was determined by reverse transcription-polymerase chain reaction. RESULTS: The lower IOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group. The histological analysis showed less inflammation and scar formation, weaker expression of collagen type IV and PCNA, more intense MMP-9 and TIMP-1, slightly elevated ratio of MMP-9 and TIMP-1, and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group (P < 0.05). CONCLUSION: PDLLA/GA membranes may be promising for preventing fibrosis after GFS.

Co-transplantation of neural stem cells and Schwann cells within poly (L-lactic-co-glycolic acid) scaffolds facilitates axonal regeneration in hemisected rat spinal cord.

BACKGROUND: Various tissue engineering strategies have been developed to facilitate axonal regeneration after spinal cord injury. This study aimed to investigate whether neural stem cells (NSCs) could survive in poly(L-lactic-co-glycolic acid) (PLGA) scaffolds and, when cografted with Schwann cells (SCs), could be induced to differentiate towards neurons which form synaptic connection and eventually facilitate axonal regeneration and myelination and motor function. METHODS: NSCs and SCs which were seeded within the directional PLGA scaffolds were implanted in hemisected adult rat spinal cord. Control rats were similarly injured and implanted of scaffolds with or without NSCs. Survival, migration, differentiation, synaptic formation of NSCs, axonal regeneration and myelination and motor function were analyzed. Student's t test was used to determine differences in surviving percentage of NSCs. One-way analysis of variance (ANOVA) was used to determine the differences in the number of axons myelinated in the scaffolds, the mean latency and amplitude of cortical motor evoked potentials (CMEPs) and Basso, Beattie & Bresnahan locomotor rating scale (BBB) score. The χ(2) test was used to determine the differences in recovery percentage of CMEPs. RESULTS: NSCs survived, but the majority migrated into adjacent host cord and died mostly. Survival rate of NSCs with SCs was higher than that of NSCs without SCs ((1.7831 ± 0.0402)% vs. (1.4911 ± 0.0313)%, P < 0.001). Cografted with SCs, NSCs were induced to differentiate towards neurons and might form synaptic connection. The mean number of myelinated axons in PLGA + NSCs + SCs group was more than that in PLGA + NSCs group and in PLGA group ((110.25 ± 30.46) vs. (18.25 ± 3.30) and (11.25 ± 5.54), P < 0.01). The percentage of CMEPs recovery in PLGA + NSCs + SCs group was higher than in the other groups (84.8% vs. 50.0% and 37.5%, P < 0.05). The amplitude of CMEPs in PLGA + NSCs + SCs group was higher than in the other groups ((1452.63 ± 331.70) µV vs. (428.84 ± 193.01) µV and (117.33 ± 14.40) µV, P < 0.05). Ipsilateral retransection resulted in disappearance again and functional loss of CMEPs for a few days. But contralateral retransection completely damaged the bilateral motor function. CONCLUSIONS: NSCs can survive in PLGA scaffolds, and SCs promote NSCs to survive and differentiate towards neurons in vivo which even might form synaptic connection. The scaffolds seeded with cells facilitate axonal regeneration and myelination and motor function recovery. But regenerating axons have limited contribution to motor function recovery.

Functional recovery following traumatic spinal cord injury mediated by a unique polymer scaffold seeded with neural stem cells and Schwann cells.

BACKGROUND: The most important objective of transplant studies in the injured spinal cord has been to provide a favorable environment for axonal growth. Moreover, the continuing discovery of new grafts is providing new potentially interesting transplant candidates. Our purpose was to observe the morphological and functional repair effects of the co-transplantation of neural stem cell (NSC), Schwann cells (SCs) and poly lactide-co-glycolide acid (PLGA) on the spinal cord injury of rats. METHODS: A scaffold of PLGA was fabricated. NSCs and SCs were cultured, with the NSCs labeled with 5-bromodeoxyuridine, and the complex of NSC/PLGA or NSC + SCs/PLGA were constructed. Thirty-six Wistar rats were randomly divided into three groups: group A (transplantation of PLGA), group B (transplantation of NSC/PLGA) and group C (transplantation of NSC + SCs/PLGA). The 3 mm length of the right hemicord was removed under the microscope in all rats. The PLGA or the complex of PLGA-cells were implanted into the injury site. Basso-Beattie-Bresnahan (BBB) locomotion scores, motor and somatosensory evoked potential of lower limbs were examined to learn the rehabilitation of sensory and motor function at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. All the recovered spinal cord injury (SCI) tissues were observed with HE staining, immunohistochemistry, and transelectronmicroscopy to identify the survival, migration and differentiation of the transplanted cells and the regeneration of neural fibres at 4 weeks, 8 weeks, 12 weeks and 24 weeks after injury. RESULTS: (1) From 4 weeks to 24 weeks after injury, the BBB locomotion scores of cell-transplanted groups were better than those of the non-cell-transplanted group, especially group C (P < 0.05). The amplitudes of the somatosensory evoked potential (SEP) and motor-evoked potential (MEP) were improved after injury in groups B and C, but the amplitude of SEP and MEP at 4 weeks was lower than that at 12 weeks and 24 weeks after injury. Compared with group B, the amplitude of SEP and MEP in group C was improved. The amplitude of SEP and MEP was not improved after injury in group A. (2) HE staining revealed the volume of the scaffold decreased and the number of cells in the scaffold increased. Newly-grown capillaries also could be seen. Immunohistochemistry staining showed the transplanted NSCs could survive and migrate until 24 weeks and they could differentiate into neurons and oligodendrocytes. The regenerated axons were observed in the scaffold-cell complex with transelectronmicroscopy. The above manifestations were more extensive in group C. CONCLUSIONS: The transplanted NSC can survive and migrate in the spinal cord of rats up to 24 weeks after injury, and they can differentiate into various neural cells. Co-transplantation of cells/PLGA can promote the functional recovery of the injured spinal cord. The effect of co-transplanting NSC + SCs/PLGA is better than transplanting NSC/PLGA alone.

[Fabrication and characteristics of oriental poly (lactic-co-glycolic acid) scaffold: a preliminary study].

OBJECTIVE: To explore the method of fabricating oriental scaffolds and investigate the biocompatibility of the scaffolds as well as cells distribution within the scaffolds in vitro. METHODS: The oriental poly (lactic-co-glycolic acid) (PLGA) scaffolds were fabricated with modified emulsion-phase separation method. The scaffolds were treated with plasma and then anchored with collagen I. Articular chondrocytes were loaded into the scaffolds. The growth status and distributing characteristic of the cells were investigated by environmental scanning electron microscope. RESULTS: The scaffold was well compatible with the articular chondrocytes. The cells could reach to 2.5 mm depth with unilateral loading. The cells distributed evenly in the scaffold and lined along the inner pipes. CONCLUSIONS: The oriental scaffold fabricated could significantly promote the distributing characteristics of the chondrocytes. The vertical alignment of the chondrocytes within the scaffold is closely similar to that of articular cartilage.

Effect of different biomedical membranes on alkali-burned cornea.

OBJECTIVE: To evaluate the effects of different biomedical membranes on alkali-burned cornea in vivo. METHODS: 12 New Zealand rabbits were chosen and randomly divided into four groups. The right cornea of each rabbit was made into an alkali-burned model with 1 mmol/l NaOH. Poly-D,L-lactic acid (PDLLA), PDLLA modified with collagen (PDLLA/collagen) and PDLLA modified with chitosan (PDLLA/chitosan) membranes were transplanted onto the alkali-burned corneas for evaluation. Clinical evaluations were performed daily with a slit lamp. On the 12th day after surgery, the progress in wound healing was compared by clinical and histological examination. The reepithelialization of each cornea was evaluated with fluorescein staining and 3 corneas of each group were excised to observe histological changes such as corneal wound healing, inflammation and collagen synthesis. RESULTS: The wound healing rate of the PDLLA/chitosan group was higher than in the other groups. A more orderly arrangement of collagen and mild inflammation was observed. The control group had the next best performance, while the PDLLA/collagen and PDLLA alone treatment groups showed the worst results. CONCLUSION: PDLLA/chitosan promoted wound healing of alkali-burned corneas in vivo and decreased scar tissue formation, while the effect of the PDLLA/collagen and PDLLA membranes was to promote corneal ulcers, which suggests that PDLLA/chitosan membrane transplantation is a potential effective strategy for treatment of alkali-burned cornea.

[Research about schwann cells and PLGA implanted to rat transected spinal cord].

OBJECTIVE: To investigate the recovery of rat transected spinal cord injury after implantation of Schwann cells combined with poly (lactide-co-glycolide) (PLGA). METHODS: Schwann cells were expanded, co-cultured with PLGA for 9 days in vitro, and then analyzed with scanning electron microscope (SEM). Rat spinal cord at the level of T(9) was transected. Schwann cells labeled with BrdU and PLGA scaffold were implanted to injury site. After 1, 3, 6 months, BrdU/MBP immunohistochemistry double staining, semi-thin sections stained thionin and ultra-thin section were performed to investigate myelin renew. BBB open field locomotion, motor evoked potential (MEP), compound muscle action potential (CMAP) and somatosensory evoked potential (SEP) were recorded. RESULTS: Schwann cells grew well on PLGA under SEM. BrdU/MBP double positive cells would been seen, remyelination was thin and formed by Schwann cells at 6 months later under electron microscope (EM). BBB behavioral tests revealed no significant difference in recovery comparing with experiment group and control group. The results of MEP, CMAP and SEP showed no significant improvement in the conduction of spinal cord. CONCLUSIONS: There are the compatibility between Schwann cells and PLGA. Although remyelination was found in morphology, function conduction of spinal cord failed to be established.

[A pharmacodynamics study of an intravitreal amphotericin B drug delivery system for the treatment of experimental Aspergillus fumigatus endophthalmitis].

OBJECTIVE: To observe a new amphotericin B drug delivery system (AmB-DDS), and investigate the therapeutic effects of AmB-DDS on an experimental Aspergillus fumigatus endophthalmitis. METHODS: (1) In order to observe the effects of AmB-DDS, thirty-four New Zealand albino rabbits were intravitreal injected Aspergillus fumigatus suspension (10(3) colony forming unit, CFU) in applanation of vitreous body before therapy 48 hours. All models were randomly divided into five groups. Group A was the empty control group, treated nothing after Aspergillus fumigatus injection, group B was the empty DDS implantation combined with vitrectomy, no treatment after DDS implanted, group C: AmB 5 microg-injection combined with vitrectomy, the injection was repeated two week later, group D: 250 microg AmB-DDS intravitreal implantation combined with vitrectomy, Group E: 500 microg AmB-DDS intravitreal implantation combined with vitrectomy. Aqueous flare, cells, anterior vitreous cells and vitreous opacity were graded, and vitreous humor smear and culture were performed at different time points after operation in 8 weeks. Two months after operation, light microscopy was used histology evaluation. (2) To observe the release of AmB-DDS in Group H (6 eyes), 500 microg AmB-DDS were implanted in the eye of the rabbits after vitrectomy, vitreous humor was aspirated and the concentrations of amphotericin B were determined by high performance liquid chromatography (HPLC). RESULTS: The inflammation response was lower in groups C, D, E than groups A, B. There was no significant statistical difference between group A and group B (P > 0.05), but differences among C, D, E and groups A, B were significant (P < or = 0.005). The inflammation grade was lower in group E than group C (P < or = 0.005). There was significant statistical difference between the cure effect of group E and group D (chi(2) = 10.494, P = 0.003). All of vitreous humor smears was positive in 1.5 months after surgery, but the culture was only positive in group A, and B. Pathological examination indicated that normal structure was disappeared in the eyes with Aspergillus endophthalmitis. At the first day after surgery, AmB were observed by analysis of HPLC, there was sustained AmB release in the group of AmB-DDS application during the observation periods. CONCLUSIONS: The degradable AmB-DDS can effectively suppress the inflammation of the rabbit model of Aspergillus fumigatus endophthalmitis. As an alternative to the current routine therapy, it can be used for the treatment of Aspergillus fumigatus endophthalmitis.

Human vascular smooth muscle cells and endothelial cells cocultured on polyglycolic acid (70/30) scaffold in tissue engineered vascular graft.

BACKGROUND: Current prosthetic, small diameter vascular grafts showing poor long term patency rates have led to the pursuit of other biological materials. Biomaterials that successfully integrate into surrounding tissue should match not only the mechanical properties of tissues, but also topography. Polyglycolic acid (70/30) has been used as synthetic grafts to determine whether human vascular smooth muscle cells and endothelial cells attach, survive and secrete endothelin and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha). METHODS: Endothelial cells and smooth muscle cells were isolated from adult human great saphenous vein. They were seeded on polyglycolic acid scaffold in vitro separately to grow vascular patch (Groups A and B respectively) and cocultured in vitro to grow into vascular patch (Group C). Smooth muscle cells and endothelial cells were identified by immunohistochemical analysis and growth of cells on polyglycolic acid was investigated using scanning electron microscopy. The levels of endothelin and 6-keto-PGF1alpha in the culturing solutions were examined by radioimmunology to measure endothelial function. RESULTS: Seed smooth muscle cells adhered to polyglycolic acid scaffold and over 28 days grew in the interstices to form a uniform cell distribution throughout the scaffold. Then seed endothelial cells formed a complete endothelial layer on the smooth muscle cells. The levels of endothelin and 6-keto-prostaglandin F1 alpha in the culturing solution were (234 +/- 29) pg/ml and (428 +/- 98) pg/ml respectively in Group C and (196 +/- 30) pg/ml and (346 +/- 120) pg/ml in Group B; both significantly higher than in Groups A and D (blank control group, all P < 0.05). CONCLUSIONS: Cells could be grown successfully on polyglycolic acid and retain functions of secretion. Our next step is to use human saphenous vein smooth muscle cells and endothelial cells to grow tubular vascular grafts in vitro.

[Implantation of FK506 drug delivery system into the anterior chamber for inhibiting corneal rejection in high risk rabbit corneal allograft].

OBJECTIVE: To study the effects of a biodegradable FK506 drug delivery system (DDS) on the inhibition of corneal rejection, to measure the concentration of FK506 in the aqueous humor and to study the relationship between intraocular concentration of FK506 and its immunosuppressive effects on corneal rejection. METHODS: Corneal neo-vascularization was induced by 5 - 0 silk sutures in 68 New Zealand rabbits to establish a high risk corneal transplantation model. A unilateral 7 mm diameter central penetrating corneal transplantation was performed with 7.5 mm diameter grafts from health New Zealand rabbit donors. Grafted rabbits were randomized into five groups as follows: Group A: untreated control animals; Group B: DDS anterior chamber recipients without drug; Group C: 1 mg cyclosporine DDS anterior chamber recipients; Group D: 0.1% FK506-olive oil drop recipients; Group E: 0.5 mg FK506 DDS anterior chamber recipients. Grafts were examined with a slit lamp every other day and clinical conditions were scored for up to 28 weeks. The aqueous humor and cornea of Group D and Group E were collected, and the concentration of FK506 was determined. The expression of cytokines IL-2R alpha, MCP-1, Fas and FasL mRNA was detected with in situ hybridization method. RESULTS: The median survival time was (17.9 +/- 4.7) d in Group A (untreated corneal allograft), (20.0 +/- 3.7) d in Group B, (56.3 +/- 8.8) d in Group C, (78.1 +/- 7.2) d in Group D, and over 180 d in Group E. Statistically significant difference (F = 926.37, P = 0.0000) in the survival time of allograft has been found between Group E and other groups. The concentration of FK506 in aqueous humor was (15.7 +/- 2.6) ng/ml in Group E at one week and remained stable for at least 24 weeks, much higher than that in Group D (<0.3 ng/ml). The concentration of FK506 in cornea was also higher in Group E than that in Group D. The expression of cytokines IL-2R alpha and MCP-1 mRNA was detected, but the expression of Fas and FasL mRNA was not detected in Group A. CONCLUSIONS: FK506 DDS implanted in the anterior chamber can significantly prolong corneal allograft survival in high-risk corneal graft rejection model. This intraocular DDS may be a valuable adjunct for the suppression of immune graft rejection in high-risk corneal transplants.

[Anti-infectious effect of sustained antravitreal amphotericin B drug delivery system on experimental rabbit fungal endophthalmitis of Candida albicans].

OBJECTIVE: To evaluate the efficacy and toxicity of sustained intravitreal amphotericin B drug delivery system (DDS) on experimental rabbit fungal endophthalmitis of Candida albicans. METHODS: Fifty New Zealand rabbits received central vitrectomy were followed by Candida albicans suspension (10(4) colony forming unit, cfu) injection. Rabbits were grouped randomly into five with ten in each as follows: Group A, endophthalmitis control group; Group B, DDS of vehicle alone; Group C, topical treatment with amphotericin B eyedrop; Group D, 5 microg of amphotericin B intravitreal injection every week for two weeks; Group E, DDS contained 1 mg of amphotericin B. Slit-lamp and indirect-ophthalmoscope were performed at different time for two months and vitreous opacity was compared between each group. The intraocular drug concentration was measured with high performance liquid chromatography (HPLC). Light and electron microscope were conducted to evaluate the toxicity of DDS and the effect of vehicle on intraocular structure. Electroretinography (ERG) was employed to evaluate the function of retina before and after the implantation of DDS. RESULTS: Endophthalmitis was obviously inhibited in group E while vitreous was still opacity in other groups. The drug concentration in vitreous cavity was stable and remained for two months in group E while rapidly went down two weeks later in group D. No toxic evidence was found in ocular, liver and kidney tissue and retinal ultrastructure was normal. There was no difference in ERG study before and after the DDS was implanted. CONCLUSIONS: Sustained intravitreal amphotericin B DDS can significantly suppress the formation of fungal colony and inhibit the development of infection with long and stable intraocular drug concentration maintenance. The vehicle and amphotericin B DDS are safe to intraocular structure.

[Sustained rapamycin drug delivery system in prevention of high risk corneal allograft rejection and neovascularization in rabbits].

OBJECTIVE: To evaluate the immunosuppressive and antiangiogenesis effects of rapamycin drug delivery system (RAPA DDS) in high risk rabbit model of penetrating keratoplasty (PK). METHODS: (1) RAPA DDS preparation: 50 mg of PGLC and 50 mg of RAPA were mixed as a RAPA drug delivery system. (2) High risk rabbit model: Corneal vascularization was induced in 45 New Zealand white rabbits (45 eyes) by passing 5 - 0 silk sutures in corneal stroma in each quadrant. (3) 40 rabbits with corneal neovascularization beyond three quadrants were received a unilateral 7 mm diameter central PK. The 40 were divided into four treatment groups: Group A, control group and received no therapy; Group B, 1 mg PGLC carrier was implanted in the anterior chamber; Group C, 1% RAPA eye drops was applied four times daily; Group D, 0.5 mg RAPA DDS was implanted in the anterior chamber. (4) Postoperative examination: The cornea allografts (opacity, edema and neovascularization) were examined by the slit-lamp biomicroscopy for ninety days. Rejection index (RI) and neovascularization index (NI) of these animal models were recorded. RAPA concentration in the aqueous humor was detected on 2, 4, 8 and 12 weeks in group C and D after surgery; the expressions of IL-2R, MCP-1, Fas/FasL in samples were detected with in situ hybridization; TNF-alpha and VEGF were detected with immuno-histochemical technique three weeks after the operation in all groups. Histochemical method was carried out on the procured specimens of cornea, retina, liver and kidney at ninety days. RESULTS: (1) Allografts rejection: Mean survival times in 4 trial groups were (16.5 +/- 2.5), (16.0 +/- 2.6), (47.1 +/- 13.2), (87.6 +/- 5.8) d respectively (P = 0.000). (2) Corneal neovascularization: Mean NI was 2.4 +/- 0.7, 2.1 +/- 0.5, 0.6 +/- 0.5, 0.3 +/- 0.5 (P = 0.000) 2 weeks after the operation, and the NI value was 3.8 +/- 0.5, 3.8 +/- 0.4, 0.8 +/- 0.7, 0.4 +/- 0.8 (P = 0.000) 12 weeks after the operation in groups A, B, C and D respectively. (3) RAPA concentration in aqueous humor: Mean RAPA concentration in aqueous humor was 10.7, 12.0, 9.2, 7.0 ng/ml in group D in the 2, 4, 8 and 12 weeks after the operation respectively. RAPA can not be detected in group C. (4) Cytokine expression: IL-2R, MCP-1, TNF-alpha and VEGF were overexpression in group A and B, and undetectable in group C and D. Fas and FasL were negative in all groups. (5) No inflammatory cell infiltration was found in retina, liver and kidney tissue ninety days after the surgery. CONCLUSIONS: Sustained RAPA DDS and eyedrops can prolong allograft survival and inhibit cornea neovascularization in rabbit model. However, RAPA DDS is better than eyedrops.

[Intraocular implantation of cyclosporine A drug delivery system in the treatment of experimental uveitis].

OBJECTIVE: To investigate the effects and safety of cyclosporine A drug delivery system (CsA DDS) implanted into vitreous cavity on the treatment of experimental rabbit uveitis. METHOD: A model of uveitis was established in 30 New Zealand white rabbits (30 eyes). The rabbits were randomized into control group (group A, 6 eyes), intravitreal non-medicated DDS group (group B, 6 eyes), oral CsA group (group C, 6 eyes) and intravitreal CsA DDS group (group D, 12 eyes). The inflammatory parameters such as floating cells, flaring and exudation in anterior chamber were graded. The cells infiltration and degree of opacity in vitreous were scored as well. The electroretinography and histopathological examination in eye, liver and kidney were recorded. In addition, CsA level in vitreous cavity was measured by HPLC in another 13 New Zealand white rabbits that received intravitreal implantation of CsA DDS. RESULTS: Uveitis was successfully induced in the 30 eyes. The inflammation in groups A, B and C was more severe than group D. There was no significant difference between groups D and A or B (P < 0.05). The electroretinography showed more significant b-wave depression in groups A and B than group D (P < 0.05). A large amount of inflammatory cells infiltration and marked tissue disorganization were found at ciliary body and retina in groups A and B. The mean drug level in vitreous cavity ws (491.0 +/- 481.6) ng/ml at 4 weeks, (575.2 +/-0373.2) ng/ml at 8 weeks and (301.5 +/- 128.5) ng/ml at 12 weeks. No toxicity could be detected in histological examination by light microscopy. CONCLUSION: Sustained therapeutic drug level could be achieved by implanting CsA DDS into vitreous cavity. It may effectively reduce the ocular inflammation in the rabbit model of uveitis.

Enhanced vascular-related cellular affinity on surface modified copolyesters of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBHHx).

Random copolyester of 3-hydroxybutyrate and 3-hydroxyhexanoate, short as PHBHHx, was surface modified by ammonia plasma treatment and/or fibronectin coating, respectively. The improved results were demonstrated by better growth of human umbilical vein endothelial cells (HUVECs) and rabbit aorta smooth muscle cells (SMCs) on the surface of ammonia plasma-treated PHBHHx coated with fibronectin (PFn-PHBHHx), compared with the fibronectin-coated (Fn-PHBHHx) or uncoated PHBHHx, respectively, although XPS analysis and ELISA demonstrated higher fibronectin adsorption on Fn-PHBHHx than on PFn-PHBHHx. Confocal microscopy observation showed that the specific co-localization of fibronectin with F-actin was impaired on PFn-PHBHHx, while it was almost lost on Fn-PHBHHx compared with pristine PHBHHx or plasma-treated PHBHHx (P-PHBHHx). These were attributed to the generation of new nitrogen- and oxygen-containing groups on the PHBHHx surface by the ammonia plasma treatment, which led to increased polar components that enhanced polymer surface energy and hydrophilic properties on P-PHBHHx. The most prominent effect of PFn-PHBHHx was its stimulation of HUVECs proliferation. HUVECs on PFn-PHBHHx formed a confluent monolayer after 3 days of incubation, while SMCs were unable to form a sub-confluent layer. The above evidences revealed that PFn-PHBHHx would benefit endotheliazation rather than SMCs proliferation. We therefore believed that PFn-PHBHHx would be a promising material as a luminal surface of vascular grafts.

[Drug release and biocompatibility of cyclosporine A drug delivery system implanting into the anterior chamber].

OBJECTIVE: To study the drug concentration in the aqueous humor and the biocompatibility of cyclosporine A drug delivery system (CsA DDS) implanting in the anterior chamber. METHODS: There were four different types of CsA DDS which had different biodegradable polymers as the vector or had different ratio between CsA and the vector. Thirty-six New Zealand rabbits were randomly divided into 4 groups to receive the 4 different types of CsA DDS. Three of nine New Zealand rabbits received CsA DDS in one eye and empty DDS in the contralateral eye. Three rabbits received empty DDS in one eye and keratotomy in the contralateral eye. Another three rabbits received CsA DDS in one eye and keratotomy in the contralateral eye. All DDS were implanted into the anterior chamber. The follow-up period was 12 weeks. RESULTS: No significantly acute or chronic intraocular toxic effects were found in all groups. The CsA release rate was different in these 4 groups. In type A and B CsA DDS, the drug released fast and maintained for a short period; in type C and D, the drug released slowly and could be maintained for a long period. CONCLUSION: CsA DDS implanted in the anterior chamber can be well tolerated in rabbit eyes. CsA DDS is a promising approach for the prevention (type C and D CsA DDS) and treatment (type A and B CsA DDS) of corneal graft rejection.