Résumé
Objective:To observe the repair effect of nano hydroxyapatite/magnesium(nHA-Mg)porous composite material modified by poly lactic acid/glycolic acid copolymer(PLGA) on the jaw bone defect of rabbits,and to elucidate the mechanisms preliminary.Methods:The mandibular defect models of 10 mm×5 mm×1 mm in the 18 rabbits were established.Nine rabbits were selected and implanted with nHA-Mg composite materials modified by PLGA in the left as experimental group and the right as blank control group;the other nine were implanted with nHA-Mg in the left as positive control group and the right as blank control group.The rabbits were sacrificed at 4, 8, 12 weeks (respectively 3 of experimental group and positive control group every time)and the mandibular defect areas were intercepted and observed by imaging and histological examination;the sizes of the newborn trabecula area and residual materials in experimental group and positive control group were compared.Results:Compared with positive control group and blank control group, the percentage of newborn trabecula area of the rabbits in experimental group was increased (P0.05).The imaging results showed that the new bone formation can be observed in experimental group and better than positive control group and blank control group.The paraffin section results indicated that there were visible vascular tissue and newborn trabecula,the osteoblasts gathered around the bone trabecula;a lot of pits were located in the bone trabecula, and the pits contained osteocytes in experimental group.As the prolongation of time,thickened newborn trabecula, dense arrangement and trend of converting to lamellar bone were observed in experimental group.The hard tissue section results showed that the remaining amount of materials in experimental group was more than that in positive control group.Conclusion:nHA-Mg porous composite materials modified by PLGA can effectively reduce the rate of degradation in the body, promote osteogenesis and guide the bone regeneration.
Résumé
Objective To prepare a innovative VP3 gene‐loaded ultrasound microbubble decorated with TATp and SDF‐1 , having the extracellular accumulation and intracellular permeation function ,and characterize their property .Methods VP3 gene‐loaded ultrasound microbubbles were prepared with the method of W/O/W double emulsion .SDF‐1 and TATp were covalently con‐gjugated to the surface of poly‐lactic/acid‐glycolic acid(PLGA) microbubble though thioether bonds to prepare gene‐loaded targeted ultrasound mirobubbles .Their particle size ,distribution and surface potential were determined by Malvern measuring instrument . The conjugation status of TATp and SDF‐1 were evaluated by flow cytometry and confocal microscopy .Their DNA protection were identified by digestion reaction test .The vitro targeting capacity was preliminarily assessed by light microscopy and flow cytometry , and the vitro ultrasound imaging was investigated under high frequency imaging condition .Results The gene‐loaded targeted ultra‐sound mirobubbles showed regularly sphericity .The diameter was (536 .00 ± 16 .55)nm ,and showed a narrow distribution .The zeta potential was(-0 .08 ± 0 .08)mV .The average gene loading was 0 .62% ,with the average rate of 36 .13% gene encapsulation effi‐ciency .The DNA protective effect sustained 60 min without damage .Connection rate of TATp and SDF‐1 coupled with PLGA mi‐crobubbles surface was 69 .84% .The vitro targeting study showed that more targeted microbubbles stably clustered together in the tongue SCC‐15 cell membranes with the connection rate of 91 .44% ,while non‐targeted microbubbles combination rate was 12 .96% .Moreover ,the vitro ultrasound imaging was tiny dot ,even high echo .Conclusion TATp‐SDF‐1‐VP3‐PEG‐PLGA micro‐bubbles were prepared successfully ,which can efficiently target to tongue SCC‐15 cells ,and pass through the cell membranes at a short time in company with outstanding ultrasound imagings in vitro .
Résumé
Objective To investigate the preparation of a polycaprolactone (PCL)/poly (lactic acid-glycolic acid) (PLGA) degradable ureteral stent and its degradation ability in vitro.Methods From December 2010 to September 2012,degradable ureteral stent was fabricated by electrospinning,using different concentration of PCL/PLGA (5％,10％,15％,20％,25％,30％).The structure of stent was scanned by electron microscopy (SEM).The Instron system was used to test the mechanical property of those stents.The PCL/PLGA stents of different concentration (5％,15％,25％) were immerged into the urine to assess their degradable ability 7,14,21,28,35,42,49,56 days later.Results The inner diameter of the white tubular scaffold was 1.5 mm and the outer diameter was 2.0 mm.The SEM results showed that the scaffold had been made by nanofiber with the structure of multi-porous.The tension test showed that the mechanical property was enhanced with the increasing in the proportion of the PCL.The lowest stress at break was found in 5％ PCL/PLGA stent,while it was still sufficient for the mechanical criteria of degradable biomaterial.The degradation curves of different ratio of PCL/PLGA stent were close to a straight line.The 5％ PCL/PLGA stent collapsed into pieces within 28 d.The 15％ and 25％ PCL/PLGA collapsed within 42 d and 56 d,respectively.Conclusion The PCL/PLGA biodegradable ureteral stent has a good mechanical property and the degradation time can fully meet the demand of a ureteral stent.