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The effect of phagocytes in the degradation process of Poly-L-Lactide(PLLA)

Author: PuZhongXian
Tutor: JinDaDi
School: First Military Medical University
Course: Orthopedic Surgery
Keywords: PLLA particles Biodegradable materials Degradation Scanning electron microscopy TEM UHP electron microscopy Confocal microscopy Macrophages Ca2 pH Acid phosphatase NADPH oxidase Membrane potential
CLC: R318.08
Type: Master's thesis
Year: 2000
Downloads: 78
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Abstract

Biodegradable material adverse reactions implanted in the human body is implanted locally advanced aseptic inflammation (local edema), one of the main reasons is due to the degradation of the L-L-lactide (PLLA) a large number of particles, self-catalyzed hydrolysis of carboxylic acid degradation products accelerate the large accumulation of the carboxylic acid, resulting in reflux disorder. In this paper, scanning electron microscopy, transmission electron microscopy, the EHV electron microscopy, confocal microscopy and enzyme cytochemistry observed in vitro degradation of PLLA particles measured the variation of the PLLA particles degradation process in mouse peritoneal macrophages macrophages Enzymohistochemical activity after PLLA stimulus is detected the macrophage CA ^{2 , pH, membrane potential, is designed to investigate the the PLLA degradation process in the mechanism of action of the macrophages, the text is divided into three parts. PLLA microparticles in vitro degradation of the results of the (2,4,6,8 h) in the process of scanning electron microscopy showed that: after 2h incubation in PBS solution, can be the observed particles mild swelling, wrinkled and micropores (diameter 0.12 μm, a pore diameter with the incubation time is increased). Number of PLLA particulate porous surface after 4h multiply, and extend to the the PLLA particles of deep, to form a tubular tunnel, and to communicate with each other reticular tunnel. First 8H, PLLA particles surface covered with porous (diameter 0.8 m), showed a honeycomb-like, but remains spherical structure. 8h microporous fusion occurs, reduce the number of pore size, particle central tunnel merging to form a big hole, and ultimately off the formation of debris. Also found in the observation, the degradation of PLLA microparticles has a peak shaped nest the bundle shaped lamellar three ways, the most common of which is a honeycomb-shaped tunnel. Degradation rate of particles with the incubation temperature, time, a positive correlation. Formed microporous particulate degradation process, there are two: First, degradation of the early formation of primary micropores formed to extend from the surface to the internal PLLA the particles body of tube mesh tunnel, called the entrance of the tunnel; degradable formed in the late secondary micropores, protruding to the surface corrosion from the blind side of the particle internal mesh tunnel, known as the tunnel exit. The tunnel exit microporous far more than the micropores of the tunnel entrance, the particles degradation of late tunnels forming the self-catalysis to accelerate the accumulation of partial carboxylic acid product is an important reason to cause local edema, aseptic inflammation. Second, the PLLA particles macrophages electron microscopy showed that: 10 ~ 20min after incubation in PBS containing mouse peritoneal macrophages, macrophages can be a large number of phagocytic opsonin PLLA particles; 20 after 30 min particles swallowed fusion with lysosomes to form a homogeneous phagolysosomes and to clearly show AcPase activity. slice of the reaction in m thick AcPase with the EHV electron microscopy, clearly show the honeycomb-like lamellar particle three-dimensional structure, the results are consistent with the scanning electron microscope. Reference the same the Bu ** A intracellular degradation of extracellular degradation yl wood, but intracellular degradation significantly accelerated, acceleration effect of the tunnel is formed, this phenomenon prompted the corrosive environment within the cell is superior in vitro drop \u0026 8. Macrophage phagocytosis of PLLA particles change the outcome of the physical and chemical properties that: macrophages in the addition of solution containing PLLA particles cytosolic free Ca 'rises 30%; macrophages pH value decreased by 70 to 80%; mitochondrial membrane potential was decreased by approximately go%; membrane potential increased 100% in a short period of time; ** DPH oxidase activity rapidly increased the IS0 results suggest that the cytoplasmic acidification contribute to the activation of lysosomal enzymes, and promote macrophage endocytosis, macrophage mitochondrial membrane potential drop is caused due to a large number of phagocytic PLLA apoptosis; membrane potential rise is Ca 'cause membrane depolarization due to massive influx of help PLLA particles being swallowed;; NADPH oxidation activity increased 150%, indicating that PLLA particles stimulate macrophages, macrophages respiratory burst in a very short period of time that will help T 'macrophages remove foreign bodies.}

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