Preparation of silk fibroin/hyaluronic acid composite hydrogel based on thiol-ene click chemistry / 浙江大学学报·医学版

OBJECTIVES@#To design and prepare silk fibroin/hyaluronic acid composite hydrogel.@*METHODS@#The thiol modified silk fibroin and the double-bond modified hyaluronic acid were rapidly cured into gels through thiol-ene click polymerization under ultraviolet light condition. The grafting rate of modified silk fibroin and hyaluronic acid was characterized by 1H NMR spectroscopy; the gel point and the internal microstructure of hydrogels were characterized by rheological test and scanning electron microscopy; the mechanical properties were characterized by compression test; the swelling rate and degradation rate were determined by mass method. The hydrogel was co-cultured with the cells, the cytotoxicity was measured by the lactate dehydrogenase method, the cell adhesion was measured by the float count method, and the cell growth and differentiation on the surface of the gel were observed by scanning electron microscope and fluorescence microscope.@*RESULTS@#The functional group substitution degrees of modified silk fibroin and hyaluronic acid were 17.99% and 48.03%, respectively. The prepared silk fibroin/hyaluronic acid composite hydrogel had a gel point of 40-60 s and had a porous structure inside the gel. The compressive strength was as high as 450 kPa and it would not break after ten cycles. The water absorption capacity of the composite hydrogel was 4-10 times of its own weight. Degradation experiments showed that the hydrogel was biodegradable, and the degradation rate reached 28%-42% after 35 d. The cell biology experiments showed that the cytotoxicity of the composite gel was low, the cell adhesion was good, and the growth and differentiation of the cells on the surface of the gel were good.@*CONCLUSIONS@#The photocurable silk fibroin/hyaluronic acid composite hydrogel can form a gel quickly, and has excellent mechanical properties, adjustable swelling rate and degradation degree, good biocompatibility, so it has promising application prospects in biomedicine.

Evidencia clínica y microscópica de la degradación de hilos de dermosustentación de polidioxanona en presencia de ácido hialurónico: reporte de caso / Microscopic and clinical evidence of the degradation of polydioxanone lifting threads in the presence of hyaluronic acid: a case report

Se expone el caso de una paciente remitida por complicaciones posteriores a la implantación superficial en el tercio medio facial de hilos de polidioxanona espiculados. Presentaba edema, equimosis, palpación superficial del hilo y plicación dérmica. Para el tratamiento planteamos un novedoso protocolo de degradación clínica de hilos de polidioxanona, empleando ácido hialurónico inyectándolo en el área de su implantación. Se infiltró ácido hialurónico no reticulado en el trayecto a lo largo del recorrido del hilo. El seguimiento a los siete, 21 y 45 días evidenció disminución del edema, de los pliegues e irregularidades dérmicas por la tracción del hilo y atenuación de rítides secundarias. Una muestra del hilo en ácido hialurónico fue observado en campana de flujo laminar evidenciándose degradación a las 72 horas. Administrar ácido hialurónico fue efectivo para inducir la biodegradación clínica del hilo. La hipótesis derivada sugiere que el ácido hialurónico no reticulado es un poderoso catalizador de la degradación hidrolítica de la polidioxanona.

We present the case of a female patient with complications from superficial implantation of polydioxanone spiculated threads in the facial middle third. The manifestations were edema, ecchymosis, superficial palpation of the thread and skin plication. For the treatment we propose a novel protocol of clinical degradation of polydioxanone threads, using hyaluronic acid injecting it into the implantation area of the polydioxanone threads. Non-cross linked hyaluronic acid was infiltrated along the path of the thread. The follow-up at seven, 21 and 45 days showed decreased edema, folds and skin irregularities due to wire traction and attenuation of secondary rhytides. A sample of the thread in hyaluronic acid was observed in a laminar flow campaign evidencing degradation at 72 hours. Administering hyaluronic acid was effective in inducing clinical biodegradation of the thread suggesting that non-crosslinked hyaluronic acid is a powerful catalyst for the hydrolytic degradation of polydioxanone.

To what extent does hyaluronic acid affect healing of xenografts? A histomorphometric study in a rabbit model

ABSTRACT Among the many graft materials that have been used for the treatment of bone defects in oral and maxillofacial regions is xenograft. To improve osteoconductive effects of xenografts, they have been combined with various biocompatible materials, such as hyaluronic acid and bone morphogenetic protein. Objective: To determine bone-healing capacity of high molecular weight hyaluronic acid (HA) combined with xenograft in rabbit calvarial bone defects. Material and methods: Ten adult male New Zealand rabbits (mean weight 3 kg) were included in the study. Three 6-mm-diameter bicortical cranial defects were created on calvarial bone of all rabbits. These defects were filled as follows: a) xenograft; b) HA+xenograft; c) autograft. One month after the first operation, rabbits were sacrificed. Specimens were evaluated histomorphometrically. Results: Considering multiple comparisons, differences regarding new bone were statistically significant between all groups (p<0.05). The volume of residual graft was significantly decreased in HA group compared to xenograft group (p=0.035). Marrow space, trabecular thickness (TbTh), trabecular width (TbWi), trabecular separation (TbSp), and number of node: number of terminus (NNd:NTm) in the autograft group were significantly better than xenograft and HA groups (p<0.05). However, regarding marrow space, TbTh, TbWi, TbSp, and NNd:NTm values, xenograft and HA groups showed similar results and the difference were not significant (p>0.05). Conclusion: These results support that high molecular weight hyaluronic acid could contribute to the healing of xenograft by improving the percentage of new bone formation and reducing the percentage of residual graft. However, HA did not significantly affect the quality of newly formed bone assessed by microarchitectural parameters.

Hyaluronic acid: A promising mediator for periodontal regeneration .

Hyaluronic acid (HA) is a natural-non sulphated high molecular weight glycosaminoglycan that forms a critical component of the extracellular matrix and contributes significantly to tissue hydrodynamics, cell migration and proliferation. The use of HA in the treatment of inflammatory process is established in medical areas such as orthopedics, dermatology and ophthalmology. In the field of dentistry, hyaluronate has shown anti-inflammatory, antiedematous and anti-bacterial effects for the treatment of gingivitis and periodontitis. Due to its potential role in modulation of wound healing, its administration to periodontal wound sites could achieve comparable beneficial effects in periodontal tissue regeneration and periodontal disease treatment.

Characterization of a gelatin/chitosan/hyaluronan scaffold-polymer

Gelatin, chitosan and hyaluronic acid are natural components used to prepare polymeric scaffold in tissue engineering. The physical properties of these materials confer an appropriate microenvironment for cells, which can be used as a regeneration system for skin and cartilage. In this work, we prepared and characterized a Gelatin/Chitosan/Hyaluronan lyophilized-polymer. Physical properties of lyophilized-polymer changed slightly with moisture, but when polymer was totally hydrated the elasticity changed significantly. Thermophysical characterisation indicated that temperatures higher than 30ºC could modify irreversibly the polymeric matrix probably due to protein denaturation. Besides, we used the polymer as scaffold to prepare a biosynthetic-skin, reporting biological behaviour and its mechanical properties.

In vivo visualization of bonghan ducts inside blood vessels of mice by using an Alcian blue staining method.

An in vivo method using Alcian blue (AB) was developed for visualizing floating threadlike tissues inside blood vessels of mice. These novel structures called intravascular Bonghan ducts (IBHDs) are considered as extension of acupuncture meridians. For in vivo imaging of IBHDs, AB solution (pH 7.4) that stains mucopolysaccharides like hyaluronic acid was used. After injecting AB solution into the femoral vein of a mouse, the threadlike structures, stained deep blue, inside the inferior vena cava. The histological results, such as hematoxylin, eosin, and AB staining, show the compositions of the cells and the extracellular matrix in the IBHD. Further studies are needed to investigate their physiological functions, especially in relation with those of other circulatory systems.

Evidence for clustered mannose as a new ligand for hyaluronan- binding protein (HABP1) from human fibroblasts.

We have earlier reported that overexpression of the gene encoding human hyaluronan-binding protein (HABP1) is functionally active, as it binds specifically with hyaluronan (HA). In this communication, we confirm the collapse of the filamentous and branched structure of HA by interaction with increasing concentrations of recombinant-HABP1 (rHABP1). HA is the reported ligand of rHABP1. Here, we show the affinity of rHABP1 towards D-mannosylated albumin (DMA) by overlay assay and purification using a DMA affinity column. Our data suggests that DMA is another ligand for HABP1. Furthermore, we have observed that DMA inhibits the binding of HA in a concentration-dependent manner, suggesting its multiligand affinity amongst carbohydrates. rHABP1 shows differential affinity towards HA and DMA which depends on pH and ionic strength. These data suggest that affinity of rHABP1 towards different ligands is regulated by the microenvironment.