Preparation and characterization of a novel antimicrobial film dressing for wound healing application

Antibacterial activity and good mechanical properties are some of the characteristics required for an appropriate film dressing. A novel polymer blend was developed for wound healing application. Twenty-four formulations using the polymers chitosan, poly(vinyl alcohol) and/or ɛ-Polylysine and the plasticizer glycerol were designed using factorial design and then the films were prepared by the casting/solvent evaporation method. Seventeen films were obtained among the twenty-four proposed formulations that were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Mechanical properties, such as tensile strength (σ), elongation at break (ɛ) and Young's modulus (Y) as well as antibacterial properties were determined. The best candidate was then further analyzed with regard to porosity, Water Vapor Transmission Rate (WVTR), swelling and cytotoxicity experiments. The results showed a film with semi-occlusive characteristics, good mechanical properties and no toxic. Incorporation of ɛ-Polylysine increased antibacterial activity against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria

Effect of oxygen-vectors on the production of ε-poly-L-lysine / 生物工程学报

To enhance the production of ε-poly-L-lysine (ε-PL) by improving dissolved oxygen level of the fermentation system, different oxygen-vectors were added to broth and n-dodecane was screened as the best oxygen-vector. The best amount of n-dodecane was 0.5% (V/V) and the best time was at start of the fermentation. In a fed-batch fermentation in a 5 L bioreactor, ε-PL concentration reached a maximum of (30.8 ± 0.46) g/L and the dry cell weight obtained was (33.8 ± 0.29) g/L, increasing by 31.6% and 20.7% compared with the control group, respectively. This improvement can be related to 0.5% n-dodecane could maintain dissolved oxygen concentration > 32% of air concentration compared with 23.8% in ε-PL production phase, and the production of a main by-product, poly-L-diaminopropionic acid, fell by 31%. These results indicated that the dissolved oxygen level in the broth was improved by adding n-dodecane, which can inhibit the by-product production and improve the biosynthesis of ε-PL.

Enhanced ε-poly-L-lysine production through pH regulation and organic nitrogen addition in fed-batch fermentation / 生物工程学报

During the production of ε-poly-L-lysine (ε-PL) in fed-batch fermentation, the decline of ε-PL synthesis often occurs at middle or late phase of the fermentation. To solve the problem, we adopted two strategies, namely pH shift and feeding yeast extract, to improve the productivity of ε-PL. ε-PL productivity in fermentation by pH shift and feeding yeast extract achieved 4.62 g/(L x d) and 5.16 g/(L x d), which were increased by 27.3% and 42.2% compared with the control ε-PL fed-batch fermentation, respectively. Meanwhile, ε-PL production enhanced 36.95 g/L and 41.32 g/L in 192 h with these two strategies, increased by 27.4% and 42.48% compared to the control, respectively. ε-PL production could be improved at middle or late phase of fed-batch fermentation by pH shift or feeding yeast extract.

SPIO-labeled rat bone marrow mesenchymal stem cells: alterations of biological activity and labeling efficiency assay in vitro / 生物医学工程学杂志

This study aimed to characterize and magnetic resonance imaging (MRI) track the mesenchymal stem cells labeled with polylysine-coated superparamagnetic iron oxide (PLL-SPIO). Rat bone marrow derived mesenchymal stem cells (rMSCs) were labeled with 25, 50 and 100 microg/mL PLL-SPIO for 24 hours. The labeling efficiency was assessed by iron content, Prussian blue staining, electron microscopy and in vitro MR imaging. The labeled cells were also analyzed for cytotoxicity and differentiation potential. Electron microscopic observations and Prussian blue staining revealed that 75% -100% of cells were labeled with iron particles. PLL-SPIO did not show any cytotoxicity up to 100 microg/mL concentration. Both 25 microg/mL and 50 microg/mL PLL-SPIO labeled stem cells did not exhibit any significant alterations in the adipo/osteo/chondrogenic differentiation potential compared to unlabeled control cells. The lower concentration of 25 microg/mL iron labeled cells emitted an obvious dark signal in T1W, T2WI and T2 * WI MR image. The novel PLL-SPIO enables to label and track rMSCs for in vitro MRI without cellular alteration. Therefore PLL-SPIO may potentially become a better MR contrast agent especially in tracking the transplanted stem cells and other cells without compromising cell functional quality.

Cryopreservation of microencapsulated human hepatocytes / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To establish a stable method of isolation, culture and cryopreservation of adult primary hepatocytes to provide potential hepatocyte resources for therapeutic usage in hepatocyte transplantation and bioartificial liver support systems for the treatment of acute and chronic liver diseases,and for experimental usage as an in vitro model of the liver.</p><p><b>METHODS</b>Adult hepatocytes from 20 human donors undergoing partial hepatectomy were isolated using a two-step extracoporeal collagenase perfusion technique.Seven preincubation time points (2h,6h,12h,24h,36h,48h and 72h) were selected for optimization.After pre-incubation at 4 degrees C for 12-24h in HepatoZYME-SFM (the optimal condition),hepatocytes were microencapsulated using alginate-poly-L-lysine-alginate microcapsules,transferred to a complete medium containing 10% dimethyl sulphoxide and immediately placed into an isopropanol progressive freezing container for overnight freezing at -80 degrees C followed by immersion in liquid nitrogen the next day.During the post-thawing culture period,the cells were tested for albumin secretion,urea synthesis,cell cycling,transcription and protein synthesis (measuring mRNA and protein levels),and the morphological structure and pathology,for comparison with the features from before microencapsulated cryopreservation (PMC).</p><p><b>RESULTS</b>The viability and plating efficiency of the hepatocytes isolated using the two-step extracorporeal collagenase perfusion technique were 75.0+/-4.6% and 72.0+/-6.0%,respectively.The pre-incubation times of 12h and 24h (viability:61.4+/-4.8% and 62.0+/-5.6%; plating efficiency:3.2+/-5.8% and 62.6+/-3.6%,respectively) showed significantly higher albumin secretion than all other time points tested (F =40.3,all P less than 0.05).Compared with the immediate cryopreservation (immediately frozen control) hepatocytes,the PMC hepatocytes showed significantly better transcription and protein synthesis and higher albumin secretion and urea levels.The PMC group did not show a significantly different level of albumin production from the directly cultured hepatocytes (culture day 2:ll9.2ng/ml vs.131.36ng/ml,P =0.051; day 3:110ng/ml vs.120.4ng/ml,P=0.063; day 4:98.2ng/ml vs.109.8ng/ml,P more than 0.05).However,over culturing days 2,3 and 4,comparison of the PMC hepatocytes to the immediate cryopreservation hepatoeytes showed the former to have significantly higher secretion of albumin (119.2ng/ml vs.101.2ng/ml,110.0ng/ml vs.87.6ng/ml and 98.2ng/ml vs.73.8ng/ml; all P less than 0.05) and urea level (7.83 mug/ml vs.6.79 mug/ml,6.83 mug/ml vs.5.89 mug/ml and 5.85 mug/ml vs.4.83 mug/ml; all P less than 0.05).The post-thawed PMC hepatoeytes showed preservation of the morphological structure,while the immediate cryopreservation hepatocytes did not.</p><p><b>CONCLUSION</b>The two-step extracorporeal collagenase perfusion technique after partial hepatectomy is a novel,simple,and reliable method for hepatocyte isolation.Pre-incubation at 4 degrees C for 12-24h before the microencapsulation cryopreservation allows for efficient recovery of functional and morphological integrity after thawing and provides viable hepatoeytes that may be useful for clinical applications in pharmacotoxicology,bioartificial liver therapy and cell therapy in humans.</p>

Synthesis and experimental study of a novel polymer/gene compound drug controlled release system for the treatment of erectile dysfunction / 中华男科学杂志

<p><b>OBJECTIVE</b>To overcome the deficiency in the current therapies for erectile dysfunction (ED), we designed and synthesized a novel high-efficiency polymer/gene compound drug controlled release system and discussed the feasibility of pH and temperature dually sensitive injectable hydrogel in ED gene therapy.</p><p><b>METHODS</b>We synthesized optimal siRNA gene nanoparticles by characterizing the zeta potential of polylysine (PLL)/siRNA gene compounds, and established a pH and temperature dually sensitive injectable gene compound drug controlled release system via Schiffs reaction between glycol chitosan (GC) and benzaldehyde capped OHC-PEO-PPO-PEO-CHO. Then we demonstrated the sustained release of the system at different temperatures.</p><p><b>RESULTS</b>When the mass ratio of PLL to siRNA was 20:1, the zeta potential of the PLL/siRNA gene compound reached the peak (+23.5 mV) and the siRNA was encapsulated by PLL in the maximal degree. GC and OHC-PEO-PPO-PEO-CHO was crosslinked via benzoicimine reaction when environmental pH was changed from 5.5 to 7.4. The reslease of the siRNA encapsulated in this system kept at a low rate at 37 degrees C, significantly enhanced with the increase of the temperature to 60 degrees C, rising to (122.5 +/- 5.3) microg at 1 000 minutes as compared with (23.8 +/- 6.0) microg at 37 degrees C (P < 0.05).</p><p><b>CONCLUSION</b>The polymer/gene compound drug controlled release system was successfully synthesized, which improved the stability and capacity of gene carriers and achieved siRNA release at different temperatures, promising to be a new approach to the gene therapy of ED.</p>

Polymeric Gene Delivery for Diabetic Treatment

Several polymers were used to delivery genes to diabetic animals. Polyaminobutyl glycolic acid was utilized to deliver IL-10 plasmid DNA to prevent autoimmune insulitis of non-obese diabetic (NOD) mouse. Polyethylene glycol grafted polylysine was combined with antisense glutamic acid decarboxylase (GAD) MRNA to represent GAD autoantigene expression. GLP1 and TSTA (SP-EX4) were delivered by bioreducible polymer to stop diabetic progression. Fas siRNA delivery was carried out to treat diabetic NOD mice animal.

Study on relationship of dose-effect and time-effect of APA microencapsulated bovine chromaffin cells on pain treatment / 生物医学工程学杂志

This study was to investigate the relationship of dose-effect and time-effect of Alginate-Polylysine-Alginate (APA) microencapsulated bovine chromaffin cells on the treatment of pain model rats. Using a rat model of painful peripheral neuropathy, the antinociceptive effects of APA microencapsulated bovine cells transplanted into the subarachnoid space was evaluated by cold allodynia test and hot hyperalgesia test. Compared with control group, the withdrawal difference with cell number 50 thousands groups, 100 thousands groups and 200 thousands groups was reduced (P < 0.05), and the difference decreased with the cells increases, indicating a significant analgesic effect. There was no significant difference between 400 thousands groups and 200 thousands groups. This analgesic effect maintained longer than 12 weeks. There was a positive correlation between the analgesic effect and the quantity of APA microencapsulated bovine chromaffin cells which were transplanted to treat pain model rats, and the effective antinociception remained longer than 12 weeks.

The influence on the growth of endothelial cells onto titanium-oxide films modified by poly-L-lysine and immobilized with fibronectin / 生物医学工程学杂志

In this work, a surface biological and chemical modification method was used for improving the biological behavior of endothelial cells onto titanium-oxide films. The titanium-oxide films were first activated by HCl and H2O2 to produce hydroxyl group, then coated with poly-L-lysine and further immobilized with fibronectin. The surface characteristics of samples were analyzed by Fourier Transfer Infrared Spectrum, X-ray Photoelectron Spectroscopy and contact angle method. The biological behavior of cultured human umbilical vein endothelial cell (HUVEC) seeding onto different samples surface was evaluated by the in vitro HUVEC original cultured experiment. The results showed that the method of coating with poly-L-lysine and immobilizing with fibronectin can promote the adhesion and growth of endothelial cells onto titanium-oxide film.

Growth and metabolism of osmo-sensentive yeast Y02724 and high-osmotic resistant yeast Hansel in alginate-chitosan-alginate microcapsules / 生物工程学报

To study the effect of the osmotic stress in the microenvironment on the growth and metabolism of the encapsulated cells under aerobic condition, Osmo-sensitive yeast Y02724 and high-osmotic resistant yeast Hansel were used as models to explore the growth and metabolism state of the cells cultivated inalginate-chitosan-alginate (ACA) microcapsules. The changes of the yeast cells' specific growth rate, maximum product quantity and the secretion of ethanol and glycerol were analyzed. For Y02724, the yield of ethanol was increased in the ACA microenvironment compared to suspension cultivation. For Hansel, the maximum growth speed of microencapsulated cultivation had no obvious difference compared to the suspension cultivation. Moreover, after encapsulation, the production of glycerol was decreased for both Y02724 and Hansel compared to suspension cultivation. In conclusion, osmotic stress existed in the ACA microcapsules and affected the growth and metabolism of the cells.

Preparation of polyelectrolyte multilayer film-coated microbubble ultrasound contrast agent / 中国医学科学院学报

<p><b>OBJECTIVE</b>To prepare polyelectrolyte multilayer film-coated microbubble ultrasound contrast agent (UCA) and evaluate its effects in contrast imaging on normal rabbit's liver parenchyma.</p><p><b>METHODS</b>Perfluorocarbon (PFC) -containing microbubble UCA (ST68-PFC) were prepared by sonication-based on surfactants (Span 60 and Tween 80). Subsequently, the resulting ST68-PFC microbubbles were coated using oppositely charged polylysine (PLL) and alginate (Alg) by microbubble-templated layer-by-layer self-assembly technique via electrostatic interaction. The enhancement effects in contrast imaging on normal rabbit's liver parenchyma were assessed.</p><p><b>RESULTS</b>The obtained microbubble UCA exhibited a narrow size distribution. The polyelectrolytes were successfully assembled onto the surface of ST68-PFC microbubbles. In vivo experiment showed that polyelectrolyte multilayer film-coated UCA effectively enhanced the imaging of rabbit's liver parenchyma.</p><p><b>CONCLUSIONS</b>The novel microbubble UCA obtained via layer-by-layer self-assembly, when enabling more functions, has no obvious difference in enhancement effects compared with the premodified microbubbles. The polymers with chemically active groups (such as amino group and carboxyl group) can be used as the outermost layer for the attachment of targeting ligands to microbubbles, which allows the selective targeting of the microbubbles to desired sites.</p>

Optimización de cultivos de hepatocitos humanos para estudios de citotoxicidad / Optimization of human hepatocyte cultures for citotoxicity studies

Los cultivos de hepatocitos entregan un valioso acercamiento al estudio de las funciones metabólicas específicas del hígado, evaluación de citotoxicidad. No existen líneas humanas inmortales con función normal. La inmortalización de hepatocitos humanos con el método UCHT1(medio de cultivo condicionado por células tumorales de tiroides) permitirá prolongar la sobrevida y función de estos, siendo útil para evaluar funcionalidad y citotoxicidad. Objetivo: Optimizar el cultivo de hepatocitos humanos. Metodología: En cultivos primarios de hepatocitos humanos, se agregó medio UCHT1 cultivando en superficies de colágeno, polilisina, gelatina y matrigel. Como control positivo, se utilizó línea Gherschenson (GER) para evaluar curva de crecimiento y producción de Glucógeno (PAS). Se evaluó citotoxicidad (LIVE/DEAD) en hepatocitos GER expuestos a Metotrexato (10, 100 y 1000 mM) a 24, 48 y 72 hrs. Resultados: Se realizó 3 cultivos primarios. Fue efectiva la utilización de Polilisina y Colágeno. Duración 8 meses. No se ha realizado la curva de crecimiento, ni evaluación de funcionalidad en hepatocitos humanos. La línea GER tiene un crecimiento exponencial (tiempo duplicación: 36 hrs). Se observó producción de glucógeno en condiciones de diferenciación hasta 120 hrs. La citotoxicidad por Metotrexato tiene una curva dosis dependiente, significativa en todas las concentraciones (p<0,001) (CL50 a 1000 mM a 24 hrs). Conclusiones: Se logró establecer una línea primaria de hepatocitos humanos. La polilisina y el colágeno han optimizado el establecimiento de cultivos primarios. El método PAS permitió evaluar producción de glucógeno (diferenciación). Los valores de citotoxicidad demostraron un efecto dosis dependiente en las condiciones experimentales. Logrando estandarizar el método para evaluación futura de líneas celulares humanas.

Background: Hepatocyte cultures are a valuable tool to study specific metabolic liver functions and cytoxicity. Human hepatocyte cell lines with normal function do not exist. Immortalization of human hepatocytes with a rat thyroid cell line (UCHT1) allows long-term survival and function of these cells, becoming useful to evaluate functionality and cytotoxicity. Aim: To optimize long-term culture of human hepatocytes. Material and Methods: UCHT1 media was added to primary cultures of human hepatocytes, seeding in collagen, gelatin, matrigel and polilisine surfaces. Gherschenson cell line (GER) was used as a positive control to evaluate the growth curve and Glycogen production (PAS). Cytotoxicity was evaluated (LIVE/ DEAD) in GER hepatocytes exposed to Metotrexate (10, 100 and 1000 µM) 24, 48 and 72 hrs. Results: Three primary cultures were made. The use of Polilisine and Collagen was effective. Cultures were kept for 8 months. Growth curves or evaluation of functionality in human hepatocytes, were not carried out. GER cell line had an exponential growth (duplication time: 36 hrs). Production of glycogen in differentiation conditions was observed up to 120 hrs. Cytotoxicity by Metotrexate had a dose dependent curve with a 50% lethal dose calculated as 1000 µM at 24 hrs. Conclusions: A primary line of human hepatocytes was obtained. Polilisine and collagen optimized the establishment of primary cultures. PAS method allowed the evaluation of glycogen production (differentiation). Cytotoxicity demonstrated a dose dependent effect in experimental conditions.

The effect of microencapsulated NGF-expressing NIH-3T3 cells on bioengineered dermis function in vitro / 生物医学工程学杂志

Nerve growth factor (NGF) can promote the regeneration of peripheral nerve as well as contraction and reepithelization of wound. We constructed a bioengineered dermis containing microencapsulated NGF-expressing NIH-3T3 cells and study the effect of the microencapsule to the bioengineered dermis and seed cells. NGF gene was transfected into NIH-3T3 cells and enclosed into alginate-poly-L-lysine-alginate (APA) microencapsulation and cultivated in vitro. Content of NGF in microencapsules culturing supernatant was measured by enzyme linked immunosorbent assay (ELISA) method. These microencapsules were co-cultured with epidermic cells and fibroblast cells. Bioengineered dermis was constructed with NGF-expressing micorencapsules as seed cells using tissue engineering method. NIH-3T3 microencapsules, empty microencapsules, normal culture media were control groups. After one week culture, the characteristics of the dermis were described by MTT test, the content of hydroxyproline (HP), HE staining and ultrastructure photograph. We found the NGF-expressing microencapsulates can secret NGF steadly after cultured 8w in vitro, promot the proliferation of epidermic cells and secret collagen of fibroblast cells. These functions can maintaine in bioengineered dermis. So NGF-expressing NIH-3T3 microencapsulates can promote the quality of bioengineered dermis.

Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

OBJECTIVE: We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH2 and tat-CLIO. MATERIALS AND METHODS: The hNSCs (5x105 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 microgram/ml of ferumoxides, MION or CLIO-NH2, and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. RESULTS: The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15+/-0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH2, respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH2 into the hNSCs was comparable to that of tat-CLIO. CONCLUSION: For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH2 and the transfection agent PLL.

Sinerem labeling and MRI tracking of neural stem cells in vivo and in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To label rat neural stem cells (NSCs) with the complex of Sinerem, the ultrasmall superparamagnetic iron oxide (USPIO), and poly-L-lysine (PLL), and evaluate the feasibility of tracking the labeled cells with magnetic resonance imaging (MRI) in vitro and in vivo.</p><p><b>METHODS</b>Sinerem was incubated with PLL to obtain the complex of Sinerem-PLL. The mesenchymal stem cells (MSCs) isolated from the bone marrow of SD rats were cultured and induced to differentiate into the neural stem cells. The second-passage cells were cultured overnight with the Sinerem-PLL complex, after which Prussian blue staining and transmission electron microscopy were performed to observe the nanoparticles in the cytoplasm. Cell apoptosis assay was performed to assess the cell viability 1 day, 1 week, and 2 weeks after the labeling. Cell tracking with 4.7 MR system was carried out in vivo and in vitro using T(2)WI and T(2)*WI sequences.</p><p><b>RESULTS</b>The NSCs could be effectively labeled with Sinerem-PLL complex with the labeling efficiency exceeding 95%. Prussian blue staining showed numerous blue iron particles in the cytoplasm, and under transmission electron microscope, these particles accumulated in the endosomes/lysosomes. The labeling did not significantly affect the cell viability and proliferation. Remarkable low signal density changes of the labeled cells was seen on T(2)WI and T(2)*WI in vivo and in vitro.</p><p><b>CONCLUSION</b>NSCs can be effectively labeled with Sinerem-PLL complex, and MRI can be used to track the labeled cells in vivo and in vitro.</p>

The effects of drugs, ions, and poly-l-lysine on the excretory system of Schistosoma mansoni

We have been able to label the excretory system of cercariae and all forms of schistosomula, immature and adult worms with the highly fluorescent dye resorufin. We have shown that the accumulation of the resorufin into the excretory tubules and collecting ducts of the male adult worm depends on the presence of extracellular calcium and phosphate ions. In the adult male worms, praziquantel (PZQ) prevents this accumulation in RPMI medium and disperses resorufin from tubules which have been prelabelled. Female worms and all other developmental stages are much less affected either by the presence of calcium and phosphate ions, or the disruption caused by PZQ. The male can inhibit the excretory system in paired female. Fluorescent PZQ localises in the posterior gut (intestine) region of the male adult worm, but not in the excretory system, except for the anionic carboxy fluorescein derivative of PZQ, which may be excreted by this route. All stages of the parasite can recover from damage by PZQ treatment in vitro. The excretory system is highly sensitive to damage to the surface membrane and may be involved in vesicle movement and damage repair processes. In vivo the adult parasite does not recover from PZQ treatment, but what is inhibiting recovery is unknown, but likely to be related to immune effector molecules.

The construction of an in vitro model of dural cells / 中国应用生理学杂志

<p><b>AIM</b>To study the healing mechanism of duraplasty a model of rabbit dural healing was constructed in vitro and the influences of collagen, laminin, polylysine on the migration and proliferation of dural cells were compared.</p><p><b>METHODS</b>Rabbit dura pieces 1.5 cm x 1.5 cm in size were created and were perforated in their central part with a 2 mm punch to mimic a dural defect. The dural pieces were cultured in 24-well plates which had been coated with collagen, laminin and polylysine respectively and the influence of different extracellular matrix on the migration and proliferation of dural cells was observed. Cells were subcultured on slides for immunocytochemistry to identify the characteristics of dural cells. The dural healing was observed by scanning electronic microscope.</p><p><b>RESULTS</b>Only the dura pieces cultured on collagen coated wells showed migration of cells into the central defect after a period of 8-10 days and dural defect healing occurred after 13-15 days. Dural cells stained strongly positive with antibodies against vimentin and negative with VIII factor. New collagen fibers were observed in the dural defects.</p><p><b>CONCLUSION</b>A kind of cell model for dural healing was constructed successfully in vitro. Cell migration from the dural defect margin is an important mechanism in the process of wound healing after duraplasty.</p>

Cryopreservation of microencapsulated rat islets / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of alginate-polylysine-alginate (APA) microcapsules in protecting rat islet cells in cryopreservation.</p><p><b>METHOD</b>Purified rat islet cells microencapsulated with APA and free islet cells were cryopreserved for one month and then thawed for culture in RPMI 1640 overnight. The morphology of the cells was observed and their function assessed by stimulated insulin release test.</p><p><b>RESULT</b>APA microcapsulation protected the fragile islets from freezing damage by increasing the recovery rate of the cells from 68.6%+/-2.9% to 94.7%+/-1.4% (P<0.05). After incubation with high glucose (16.7 mmol/L) solution, the insulin release from the encapsulated cells after cryopreservation significantly increased in comparison with that of the nonencapsulated cells (22.6+/-1.8 mU/L vs 11.7+/-1.5 mU/L, P<0.05). In high glucose solution containing theophylline, the calculated stimulation index of the encapsulated cells was about 3 times that of the nonencapsulated cells.</p><p><b>CONCLUSION</b>APA microencapsulation may significantly increase the post-thaw recovery and improve the function for cryopreserved rat islets.</p>

Induction of hair follicle regeneration in mice ear by microencapsulated human hair dermal papilla cells / 中华整形外科杂志

<p><b>OBJECTIVE</b>To induce the hair follicle regeneration in mice ear by microencapsulated dermal papillae cells (DPs) and to investigate the permeability of fluorescein in APA microencapsulation to search the ideal diameter of microencapsulation.</p><p><b>METHODS</b>The DPs were encapsulated with alginate-polylysine-alginate by a high-voltage electric field droplet generator. The microencapsulated dermal papilla cells were xenotransplanted into the mice ears. After 6 week, the histological examination was made by microscopy. The diffusion way and speed of fluorescein into the microencapsulations were observed by confocal laser scanning microscopy. The comparison of fluorescein intensity was made in APA microencapsulations with different diameters.</p><p><b>RESULTS</b>Fully developed hair follicles could be easily identified in the skin of implanted site following xenotransplantation of microencapsulation DPs, which were different from the control groups in configuration, number, size and differentiation degree. The fluorescein was diffused gradually into the microencapsulations with a shape of concentric circularity. The fluorescein intensity inside three groups of APA microencapsulations was: small > middle > big.</p><p><b>CONCLUSIONS</b>The microencapsulated DPs retain the physiological function to induce the follicle regeneration. The APA microencapsulations with 400um diameter could ensure the nutrition and metabolite to pass in and out freely, and isolate the immunocompetent substance absolutely.</p>

Membrana de látex da seringueira (Hevea brasiliensis), com e sem polilisina a 0,1 por cento e tela de marlex na reconstrucão de defeitos iatrogênicos da parede abdominal de ratos / Seringueira's latex membrane (Hevea brasiliensis) with and without polylysine 0, 1 percent and marlex mesh for the reconstruction of iatrogenics abdominal wall defects in rats

OBJETIVO: Comparar o implante de membrana de látex da seringueira sem e com polilisina 0,1 por cento e tela de marlex na reparacão de defeitos abdominais iatrogênicos em ratos. MÉTODOS: Ressectou-se em bloco um segmento circular de aproximadamente três centímetros de diâmetro da parede muscular abdominal ventral de 31 ratos Wistar, preservando-se a pele. Os animais foram divididos em 3 grupos: grupo látex sem polilisina, grupo látex com polilisina 0,1 por cento e grupo marlex. Os animais foram sacrificados aos cinco e aos 120 dias após o procedimento cirúrgico. Fragmentos da parede abdominal foram coletados e submetidos à avaliacão histopatológica. RESULTADOS: As principais alteracões observadas nos grupos tratados com as membranas de látex sem e com polilisina 0,1 por cento foram deiscência (21 animais) e evisceracão (dois animais). A eliminacão dos implantes nos grupos tratados com látex ocorreu, em média, aos 13,8 dias. Nestes animais ocorreu a formacão de tecido conjuntivo fibroso, similar ao observado no grupo que recebeu o marlex. Outras alteracões notadas foram aderências viscero-parietais em todos os grupos avaliados. CONCLUSAO: A membrana de látex da seringueira com e sem polilisina a 0,1 por cento, quando utilizada para reconstrucão de defeitos abdominais em ratos é eliminada, em média, aos 13,8 dias após a sua implantacão, deixando uma base fibrosa de reparacão, similar à observada após a implantacão da tela de marlex.