Collagen Sheet Research Articles

Study of Carbonated Calcium Phosphate Precipitation on Collagen

Calcium phosphate biocomposites are candidate materials for bone tissue engineering due to their conductivity and biocompatibility. Calcium phosphate could be grown on collagen by precipitation method in long reaction time. Microwave irradiation is rapid method to assist precipitation by reducing reaction time. In order to study carbonated calcium phosphate precipitation on collagen and investigate the influence of microwave irradiation time, the carbonated calcium phosphate has been grown on collagen by microwave assisted precipitation method. The collagen sheets were soaked in carbonated calcium phosphate suspension prepared by using Ca(NO3)2.4H2O, (NH4)2HPO4, and NaHCO3 as starting materials, then microwave irradiated at 270 Watt for 2 minutes, 8 minutes, and 16 minutes. X-ray powder diffraction (XRD) pattern shows the transformation of dicalcium phosphate dyhydrate to apatite crystal structure. Increase in irradiation time had increased crystallinity of carbonate apatite phase. FTIR spectrum had confirmed presence of collagen, phosphate, and carbonate functional group. Scanning electron micrograph showed the presence of collagen with pore, and the carbonated calcium phosphate could attach and be deposited onto collagen.

Stem cell-derived extracellular vesicles attenuate the early inflammatory response after tendon injury and repair.

Adipose-derived stem cells (ASCs) have the potential to enhance tendon repair via paracrine regulation of the inflammatory response to injury. Extracellular vesicles (EVs), which are secreted by ASCs, have shown promise in mediating this process. This study was designed to evaluate the effect of ASC EVs on early tendon healing using a mouse Achilles tendon injury and repair model. EVs were isolated from the conditioned medium of naïve and interferonγ-primed ASCs and applied to the repair site via a collagen sheet. Tendon healing was assessed in nuclear factor-κB (NF-κB)-luciferase reporter mice up to 7 days after suture repair. As anticipated, repair site NF-κB activity increased greater than twofold following tendon repair. Treatment with EVs from primed but not naïve ASCs effectively suppressed the response. Accordingly, the pro-inflammatory genes Il1b and Ifng were both dramatically increased in repaired tendons, while primed, but not naïve ASC EVs attenuated the response. Compared with control repairs, primed ASC EVs further reduced the rate of post-repair tendon gap formation and rupture and facilitated collagen formation at the injury site. Additional experiments demonstrated that EVs target macrophages and that primed ASC EVs were most effective in blocking macrophage NF-κB activity. Collectively, the findings of this study demonstrate that primed ASC EVs, similar to ASCs, attenuate the early tendon inflammatory response after injury via modulation of the macrophage inflammatory response. Statement of clinical significance: These findings introduce a new cell-free therapy, derived from stem cells, for tendon repair with the potential for improved therapeutic efficacy and safety. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:117-127, 2020.

Biocompatibility evaluation of bioprinted decellularized collagen sheet implanted in vivo cornea using swept-source optical coherence tomography.

Corneal transplantation by full‐thickness penetrating keratoplasty with human donor tissue is a widely accepted treatment for damaged or diseased corneas. Although corneal transplantation has a high success rate, a shortage of high‐quality donor tissue is a considerable limitation. Therefore, bioengineered corneas could be an effective solution for this limitation, and a decellularized extracellular matrix comprises a promising scaffold for their fabrication. In this study, three‐dimensional bioprinted decellularized collagen sheets were implanted into the stromal layer of the cornea of five rabbits. We performed in vivo noninvasive monitoring of the rabbit corneas using swept‐source optical coherence tomography (OCT) after implanting the collagen sheets. Anterior segment OCT images and averaged amplitude‐scans were acquired biweekly to monitor corneal thickness after implantation for 1 month. The averaged cornea thickness in the control images was 430.3 ± 5.9 μm, while the averaged thickness after corneal implantation was 598.5 ± 11.8 μm and 564.5 ± 12.5 μm at 2 and 4 weeks, respectively. The corneal thickness reduction of 34 μm confirmed the biocompatibility through the image analysis of the depth‐intensity profile base. Moreover, hematoxylin and eosin staining supported the biocompatibility evaluation of the bioprinted decellularized collagen sheet implantation. Hence, the developed bioprinted decellularized collagen sheets could become an alternative solution to human corneal donor tissue, and the proposed image analysis procedure could be beneficial to confirm the success of the surgery.

Praseodymium-Cobaltite-Reinforced Collagen as Biomimetic Scaffolds for Angiogenesis and Stem Cell Differentiation for Cutaneous Wound Healing.

The present study describes the fabrication of collagen reinforced with praseodymium-cobaltite nanoparticles for wound healing applications. Praseodymium-cobaltite nanoparticles (PCNP) reinforced with collagen resulted in an increased thermal stability and decreased proteolytic susceptibility to collagen. Circular dichroism spectroscopy and ATR-FTIR (attenuated total reflection Fourier transform infrared) spectroscopy analyses confirm the intact structural integrity of the collagen sheets after cross-linking with praseodymium-cobaltite nanoparticles. Cross-linked collagen has shown to possess biocompatibility, less protein adsorption behavior, and hemocompatibility, which are the desirable properties of a wound dressing material. The nanoparticle cross-linked collagen sheets provided a proper matrix elasticity that promotes mesenchymal stem cell attachment and angiogenesis. Further, the scaffold promoted tube formation in endothelial cells. The enhancement of angiogenesis is considered to be brought about by the therapeutic potential of nanoparticle formulation. Praseodymium-cobaltite nanoparticle cross-linking increased the ductility of collagen sheets for the pro-angiogenic and stem cell differentiation ability. Also, the praseodymium-cobaltite cross-linked collagen sheets have been shown to induce a mild level of ROS (reactive oxygen species) generation in the DCFH-DA (2',7'-dichlorodihydrofluorescein diacetate) assay, which is beneficial for angiogenesis as well as wound healing. This study paves the way for exploring the therapeutic potential of rare-earth-based nanoparticles for tissue engineering applications as an alternative for traditional wound healing materials.

Principles and development of collagen-mediated tissue fusion induced by laser irradiation

The mechanism underlying tissue fusion mediated by laser irradiation remains unclear. We clarify the mechanisms underlying laser-mediated tissue fusion using a novel model. Microscopic examinations of morphological changes within the adventitia of a bovine carotid artery and a collagen sheet prepared from bovine dermis showed collagen fibril bundle loosening and collagen fibre swelling following heating at 46 °C. An incised bovine carotid artery covered with a collagen sheet to which pressure and laser heat of 40 °C–52 °C were applied created a structure that was pressure resistant to >300 mmHg. Microscopic analyses of the irradiation site showed collagen fibril interdigitation. Hence, low-temperature laser-mediated tissue fusion causes collagen fibril bundles to loosen and swell, and crimping causes the fibres to intertwine. As the temperature declines, the loosened and swollen fibrils and fibres tighten, and collagen fibre interdigitation is completed. This technology could be applied to fuse tissues during surgery.

Use of tendon to produce decellularized sheets of mineralized collagen fibrils for bone tissue repair and regeneration.

With demand for alternatives to autograft and allograft materials continuing to rise, development of new scaffolds for bone tissue repair and regeneration remains of significant interest. Engineered collagen‐calcium phosphate (CaP) constructs can offer desirable attributes, including absence of foreign body response and possession of inherent osteogenic potential. Despite their promise, current collagen‐CaP constructs are limited to nonload‐bearing applications. In this article, we describe a process for creating decellularized sheets of highly aligned, natively cross‐linked, and mineralized collagen fibrils, which may be useful for developing multilaminate collagen‐CaP constructs with improved mechanical properties. Decellularized bovine tendons were cryosectioned to produce thin sheets of aligned collagen fibrils. Mineralization of the sheets was then performed using an alternate soaking method incorporating a polymer‐induced liquid precursor (PILP) process to promote intrafibrillar mineralization, along with incorporation of physiologically relevant amounts of citrate, Mg, and carbonate. Characteristics of the produced scaffolds were assessed using energy‐dispersive X‐ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Scaffolds were also compared with both native bovine cortical bone and pure hydroxyapatite using X‐ray powder diffraction (XRD), and Fourier transform infrared spectroscopy attenuated total reflection (FTIR‐ATR). Structural and chemical analyses show that the scaffold preparation process that we described is successful in creating mineralized collagen sheets, possessing a mineral phase similar to that found in bone as well as a close association between collagen fibrils and mineral plates.

Wrapping With Basic Fibroblast Growth Factor-Impregnated Collagen Sheet Reduces Rat Sciatic Nerve Allodynia.

Autologous vein wrapping is used to treat recurrent chronic constriction neuropathy and traumatic peripheral nerve injury. However, its use is restricted due to the inability to obtain sufficiently long veins for larger grafts. We previously reported that vein-derived basic fibroblast growth factor (bFGF) promotes heme oxygenase-1 (HO-1), which reduces allodynia via its anti-inflammatory properties. To mimic vein wrapping, we developed a collagen sheet impregnated with bFGF. Chronic constriction injury (CCI) was induced in male Wistar rats as a model of sciatic nerve injury, and the rats were divided into three groups: (i) untreated after CCI surgery (control group), (ii) treated with a collagen sheet wrap impregnated with phosphate-buffered saline (PBS/CS group), and (iii) treated with a collagen sheet wrap impregnated with bFGF (bFGF/CS group). Pain behavior (von Frey test) was evaluated on postoperative days (PODs) 1, 5, 7, and 14. Quantitative polymerase chain reaction was conducted on sciatic nerve RNA to quantify HO-1 gene, Hmox1, expression. Enzyme-linked immunosorbent assay were used to determine HO-1 protein levels on POD 1. von Frey testing showed significantly greater pain hypersensitivity in the control and PBS/CS groups than the bFGF/CS group. In the bFGF/CS group, Hmox1 messenger RNA and HO-1 protein levels were significantly increased in the sciatic nerve compared with the control and PBS/CS groups on PODs 1 and 5 and POD 1, respectively. The bFGF/CS group showed decreased allodynia and HO-1 induction, as observed with vein wrapping. Therefore, local application of bFGF may be an alternative treatment strategy for compressive neuropathy and peripheral nerve trauma in clinical settings. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2258-2263, 2019.

Effect of Basic Fibroblast Growth Factor on Xenogeneic Islets in Subcutaneous Transplantation—A Murine Model

BackgroundSubcutaneous pockets provide an extrahepatic transplant site for islet grafting to treat type 1 diabetes. However, a hypoxic environment may cause central necrosis to islets and lead to graft failure. Our previous studies focused on a pre-treated subcutaneous site with basic fibroblast growth factor (bFGF) for the formation of vascular bed. In addition to neovascularization, bFGF was also shown to protect islets against oxidative stress and chemical-induced damage in vitro. Accordingly, we propose that subcutaneous islet transplantation with a bFGF-slow releasing device simultaneously can improve islet survival in vivo. MethodsA bFGF-impregnated collagen sheet was implanted in the right back of a streptozotocin-induced diabetic mouse for neovascularization. After 10 days, the sheet was removed and the rat islet-embedding gel within the immune-isolation device was transplanted (2-time operation [OP]). In another group, the diabetic mice received bFGF-impregnated gel with rat islets within the immune-isolation device simultaneously (1-time OP). ResultsDiabetic mice in 2-time OP group experienced a decrease in their non-fasting blood glucose level for a period of 10 days, and the glucose levels were lower than those of untreated diabetic mice post-implantation. However, the mice in the 1-time OP group remained hyperglycemic post-operation and showed no improvements in body weight or the area under curve in intraperitoneal glucose tolerance test. Furthermore, mice in the 2-time OP had relatively higher serum insulin levels with improved renal and metabolic biomarkers. ConclusionOur findings suggest that bFGF had no beneficial effect on a 1-time operation in subcutaneous islet transplantation.

Biodegradable collagen from Scomberomorus lineolatus skin for wound healing dressings and its application on antibiofilm properties.

The major resolution of the study was to develop a dynamic form of natural biopolymer material to improve the wound healing by inhibition of biofilm formation on the surface. The extraction of collagen was effectively prepared from Scomberomorus lineolatus fish skin. Lyophilized collagen sheet was liquefied in 0.5M acetic acid to form acidic solubilized collagen (ASC) for further analysis. Physicochemical characterization of ASC was performed by various techniques using a standard protocol. The yield of ASC form S.lineolatus is higher (21.5%) than the previous reported studies. The effect of collagen solubility is gradually decreases with increasing concentration of NaCl and collagen is mostly soluble in acidic pH conditions. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of ASC contains α chain composition of α1 and α2 subunits and was characterized as type I collagen. Ultraviolet absorption was regulated as the appropriate wavelength to optimize the collagen. Fourier-transform infrared spectroscopy and X-ray diffraction confirmed that the isolated collagen is a triple-helical structure. The biofilm formation of Pseudomonas aeruginosa was significantly reduced by collagen incorporated with isolated 3,5,7-trihydroxyflavone (collagen-TF) sheet up to 70%. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay executed on fibroblast cell lines (L929) shows that the collagen-TF sheet was 100% compatible to enrich the cell adhesion and proliferation. The current study was the first report to extract, purify, and characterize ASC from S. lineolatus fish skin and characterize as type I collagen. Based on the result, we design the natural biodegradable collagen loaded with TF compound (collagen-TF) for antibiofilm properties. Compared with different sources of polymer, fish skin collagen is more effective and can be used as a biopolymer sheet for wound healing, food, drug delivery, tissue engineering, and pharmaceutical application.

Acceleration of bone regeneration of horizontal bone defect in rats using collagen-binding basic fibroblast growth factor combined with collagen scaffolds.

BackgroundBasic fibroblast growth factor (bFGF) has been applied for periodontal regeneration. However, the application depends on bone defect morphology because bFGF diffuses rapidly from defect sites. In a previous study, collagen‐binding bFGF (CB‐bFGF) has been shown to enhance bone formation by collagen‐anchoring in the orthopedic field. The aim of this study is to demonstrate the efficacy of CB‐bFGF with collagen scaffolds in bone regeneration of horizontal bone defect.MethodsCell proliferation activity and collagen binding activity of CB‐bFGF was confirmed by WST‐8 assay and collagen binding assay, respectively. The retention of CB‐bFGF in the collagen sheet (CS) was measured by fluorescence imaging. The rat horizontal alveolar bone defect model was employed to investigate the efficacy of CB‐bFGF with collagen powder (CP). After 4 and 8 weeks, the regenerative efficacy was evaluated by microcomputed tomography, histological, and immunohistochemical analyses.ResultsCB‐bFGF had a comparable proliferation activity to bFGF and a collagen binding activity. CB‐bFGF was retained in CS longer than bFGF. At 8 weeks postoperation, bone volume, bone mineral content, and new bone area in CB‐bFGF/CP group were significantly increased compared with those in other groups. Furthermore, epithelial downgrowth was significantly suppressed in CB‐bFGF/CP group. At 4 weeks, the numbers of osteocalcin, proliferating cell nuclear antigen, and osteopontin‐positive cells at the regeneration site in CB‐bFGF/CP group were greater than those in other groups.ConclusionsCB‐bFGF/CP effectively promoted bone regeneration of horizontal bone defect possibly by sustained release of bFGF. The potential of CB‐bFGF composite material for improved periodontal regeneration in vertical axis was shown.

Preparation of Platelet-rich Fibrin Membrane over Scaffold of Collagen Sheet, its Advantages over Compression Method: A Novel and Simple Technique.

Introduction:Platelet-rich fibrin (PRF) is compressed by using various tools to make platelet-rich fibrin membrane (PRFM). Preservation of platelets and plasma content of PRFM depends on the compression method used. To overcome limitations of compression method, we prepared PRFM over scaffold of collagen sheet without using any compression device.Aims and Objective:To prepare PRFM without using any compression device over a scaffold of collagen sheet and to evaluate its efficacy in chronic nonhealing ulcer.Materials and Methods:PRFM was prepared, with minor modification in Choukron’s protocol, over a collagen sheet without using compression device. To study its efficacy and reproducibility, total 15 patients over 18 years of age with chronic, nonhealing ulcers of more than 3 months of various causes were included and patients with active wound infection were excluded.Results:We were able to prepare and reproduce PRFM by our technique. It overcomes the limitations of compression method with comparable efficacy to compression method. Results obtained on comparison at week 0, 3, and 6, by paired t-test, were found to be statistically significant (P < 0.0001).Conclusion:Preparation of PRFM with the method described is easy and reproducible. Use of collagen sheet synergistically improved wound healing.

Preparation of platelet-rich fibrin membrane over scaffold of collagen sheet, its advantages over compression method: A novel and simple technique

Preparation of platelet-rich fibrin membrane over scaffold of collagen sheet, its advantages over compression method: A novel and simple technique

Evaluation of the Suitability of Biocompatible Carriers as Artificial Transplants Using Cultured Porcine Corneal Endothelial Cells

ABSTRACTPurpose/Aim: Evaluating the suitability of bioengineered collagen sheets and human anterior lens capsules (HALCs) as carriers for cultivated porcine corneal endothelial cells (pCECs) and in vitro assessment of the cell-carrier sheets as tissue-engineered grafts for Descemet membrane endothelial keratoplasty (DMEK).Materials and Methods: pCECs were isolated, cultured up to P2 and seeded onto LinkCell™ bioengineered matrices of 20 µm (LK20) or 100 µm (LK100) thickness, and on HALC. During expansion, pCEC viability and morphology were assessed by light microscopy. ZO-1 and Na+/K+-ATPase expression was investigated by immunohistochemistry. Biomechanical properties of pCEC-carrier constructs were evaluated by simulating DMEK surgery in vitro using an artificial anterior chamber (AC) and a human donor cornea without Descemet membrane (DM).Results: During in vitro expansion, cultured pCECs retained their proliferative capacity, as shown by the positive staining for proliferative marker Ki67, and a high cell viability rate (96 ± 5%). pCECs seeded on all carriers formed a monolayer of hexagonal, tightly packed cells that expressed ZO-1 and Na+/K+-ATPase. During in vitro surgery, pCEC-LK20 and pCEC-LK100 constructs were handled like Descemet stripping endothelial keratoplasty (DSEK) grafts, i.e. folded like a “taco” for insertion because of challenges related to rolling and sticking of the grafts in the injector. pCEC-HALC constructs behaved similar to the DMEK reference model during implantation and unfolding in the artificial AC, showing good adhesion to the bare stroma.Conclusions: In vitro DMEK surgery showed HALC as the most suitable carrier for cultivated pCECs with good intraoperative graft handling. LK20 carrier showed good biocompatibility, but required a DSEK-adapted surgical protocol. Both carriers might be notional candidates for potential future clinical applications.

Hand-Maneuverable Collagen Sheet with Micropatterns for 3D Modular Tissue Engineering.

Modular tissue engineering creates a three-dimensional (3D) macroscale tissue construct from modular microscale units for complex 3D tissue reconstruction. In particular, a hydrogel sheet that is one of the module types allows easy and controllable assembly of 3D microenvironments as compared to other module types such as a microcapsule and a microfiber. However, it is difficult to manipulate a hydrogel sheet made of extracellular matrix (ECM) proteins. Thus, in this study, we propose a fabrication technique for the manipulation of thin collagen sheet containing cells with a paper support. A donut-shaped paper support was combined with the micropatterned collagen sheet by permeation of cell-collagen mixture passing through a micropatterned mold into the paper. We established a sterile method for the paper support to maintain high cell viability and intrinsic cell morphology and demonstrated an endothelial module having 3D tubular networks. The endothelial module also showed that control of the pattern length resulted in a change in the tubular size and network density within a sheet. The geometrically controlled collagen sheet modules are expected to be used for improved implantation and biologically relevant drug testing.

Streptococcus gordonii induces bone resorption by increasing osteoclast differentiation and reducing osteoblast differentiation

Streptococcus gordonii is commonly found in the periapical endodontic lesions of patients with apical periodontitis, a condition characterized by inflammation and periapical bone loss. Since bone metabolism is controlled by osteoclastic bone resorption and osteoblastic bone formation, we investigated the effects of S. gordonii on the differentiation and function of osteoclasts and osteoblasts. For the determination of bone resorption activity in vivo, collagen sheets soaked with heat-killed S. gordonii were implanted on mouse calvaria, and the calvarial bones were scanned by micro-computed tomography. Mouse bone marrow-derived macrophages (BMMs) were stimulated with M-CSF and RANKL for 2 days and then differentiated into osteoclasts in the presence or absence of heat-killed S. gordonii. Tartrate-resistant acid phosphatase staining was performed to determine osteoclast differentiation. Primary osteoblast precursors were differentiated into osteoblasts with ascorbic acid and β-glycerophosphate in the presence or absence of heat-killed S. gordonii. Alkaline phosphatase staining and alizarin red S staining were conducted to determine osteoblast differentiation. Western blotting was performed to examine the expression of transcription factors including c-Fos, NFATc1, and Runx2. Heat-killed S. gordonii induced bone destruction in a mouse calvarial implantation model. The differentiation of RANKL-primed BMMs into osteoclasts was enhanced in the presence of heat-killed S. gordonii. Heat-killed S. gordonii increased the expression of c-Fos and NFATc1, which are essential transcription factors for osteoclast differentiation. On the other hand, heat-killed S. gordonii inhibited osteoblast differentiation and reduced the expression of Runx2, an essential transcription factor for osteoblast differentiation. S. gordonii exerts bone resorptive activity by increasing osteoclast differentiation and reducing osteoblast differentiation, which may be involved in periapical bone resorption.

Catheter-independent suture probe canaloplasty with suprachoroidal drainage.

To introduce the novel technique of suture probe canaloplasty with suprachoroidal drainage (SCD) as a catheter-independent and cost-saving method to perform non-penetrating glaucoma surgery. Prospective interventional study with a 12-month follow-up. A standard 6/0 polypropylene suture is twisted in a special manner to create a double helix with a small loop at its end. Then canaloplasty with SCD is performed, but instead of using the standard canaloplasty catheter, Schlemm's canal is probed with the twisted suture. After 360° probing, a 10/0 polypropylene suture is thread through the loop and the twisted 6/0 suture is pulled backwards through Schlemm's canal. The 10/0 suture in Schlemm's canal is tied firmly and hyaluronic acid is injected into the suprachoroidal space. In total, 74 eyes that underwent suture probe canaloplasty with SCD were included. In 57 cases, probing of Schlemm's canal with the twisted 6/0 suture succeeded. Seventeen eyes had adhesions in Schlemm's canal which made probing with the suture impossible so that the surgeon switched in 12 cases to microcatheter-guided canaloplasty with SCD. While this was successful in five further cases, the adhesions seemed surely not be overcome and SCD with collagen sheet implantation was directly performed. In four additional cases after successful probing, the suture cut through trabecular meshwork; hence a 360° suture trabeculotomy was performed. After successful suture probe canaloplasty with SCD, intraocular pressure (IOP) decreased by 39.2% (from 19.8 ± 4.3mmHg with 3.4 ± 0.7 different IOP-lowering eye drops to 12.0 ± 1.9mmHg with 0.6 ± 0.9 eye drops). Three patients did not achieve sufficient IOP levels and, therefore, underwent 360° suture trabeculotomy during follow-up. No serious or sight-threatening complications occurred. Suture probe canaloplasty + SCD yields the opportunity to conduct canaloplasty with SCD more cost-effectively with a safety profile and IOP-lowering effect comparable to conventional canaloplasty. In cases where probing with the suture fails. there still remains the option to use a conventional microcatheter or to switch to SCD with collagen sheet implantation.

Osteogenic effectiveness of photo-immobilized bone morphogenetic protein-2 using different azidophenyl-natural polymer carriers in rat calvarial defect model

The osteogenetic potential of photo-immobilized azdiophenyl (Az)-natural polymers as a carrier of bone morphogenetic protein-2 (BMP-2) was assessed in 56 rats randomized to four groups. The control group comprised implanted collagen sheet with BMP-2. In the three experimental groups, the implant comprised collagen sheet with photo-immobilized BMP-2 on Az-gelatin (Az-Gel), Az-O-carboxymethyl chitosan (Az-OMC), or Az‑O‑carboxymethyl low molecular chitosan (Az-LMC). Micro-computed tomography analysis revealed more regenerated bone in Az-Gel at 8weeks. Immunohistochemical analysis at 4weeks revealed that the positively expressed cellular ratio in RUNX2-stained cells was significantly higher in Az-Gel and Az-OMC groups. At 8weeks, only the Az-Gel group showed higher positively expressed cellular ratio compared with the control group. These results demonstrate the superior osteogenetic potential of photo-immobilized BMP-2 using Az-Gel carrier in a rat calvarial defect model compared with control group. Photo-immobilization of BMP-2 using Az-gelatin could be a more effective carrier system of BMP-2 than a chitosan-based carrier system.

A Clinical Study of Collagen Dressing in Partial Thickness Burns

INTRODUCTION: Burn injuries are very painful conditions which usually heal slowly and that too with scarring. They are common entities encountered in our daily clinical practice. Dressings play a vital role in the management of burn wounds. As burn injuries are common in developing countries, there is an urgent need for a method by which these injuries heal early with less pain, discomfort and scarring. Hence a need is felt to study the effectiveness of wound healing process in collagen dressing. AIMS & OBJECTIVES: This prospective clinical study was designed to study the effectiveness of collagen dressing in partial thickness burns by means of pain score, infection rate, rate of healing, resultant scar and patient compliance. MATERIALS & METHODS: This study was conducted at Government Tirunelveli Medical College Hospital, Tirunelveli. A total of 60 patients with partial thickness burn wounds were included in this study and were applied collagen dressing. The variables analyzed were pain score, infection rate, rate of healing of the wound, resultant scar and patient compliance. INCLUSION CRITERIA: Patients with partial thickness burns involving 40% of the total body surface area, wounds older than 24 hours and facial burns are exclusion criteria for this study. RESULTS: In my study, 34 males and 26 females, infection was present in 8.3% of the patients (5/60), the average pain score in the range of 0 to 10 was 2.85, healing was achieved on an average of 11.57 days, 100% of patients in collagen dressing had good scars, patient compliance in the collagen dressing was good about 96.7%, none of the cases showed any adverse reaction to the collagen. CONCLUSION: Collagen sheet promotes early healing, decreases the need of analgesics, reduces the incidence of associated complications like infection. The morbidity of the patients is reduced as the resultant scar is better in majority of the patients using collagen. Because of the simple application and good tolerance of the membrane, collagen can be advocated as a temporary biological dressing material in partial thickness burns.

The efficacy of collagen based dressings for treatment of scald burns in under 5 years paediatric population: a non-comparative, prospective single centre experience

Background: One of the major challenges faced worldwide is management of burn wounds, particularly among the pediatric population. Immense research is going on to overcome the challenges associated with survival of these patients and healing of burnt areas. Newer dressing materials are being developed and one of them is collagen. The collagen is biocompatible. The aim was to achieve earlier and better healing of wounds, and to obviate the need for frequent change of dressings; which besides being painful, is quite troublesome in pediatric population.Methods: A prospective study was conducted in 38 patients of scald burns under-5 years of age, from October 2016 till July 2017. After thorough cleaning of burn wounds and thorough rinsing of collagen sheets with normal saline, the wounds were covered with sheets of collagen. Paraffin with chlorhexidine impregnated gauze dressing was applied over the sheet of collagen followed by dry gauze, cotton and bandage application. First dressing was opened after 5 days and then after 3 to 4 days.Results: The wounds healed in 10 to 14 days in most of them. Infection developed in one case, warranting removal of collagen sheet. None developed any adverse reaction to the application of collagen dressing.Conclusions: We conclude that collagen based dressing is a very good modality of treatment for the burn wounds with advantages of being cost effective, requiring lesser number of dressings and blood transfusions, and shorter duration of hospital stay.

Internal Fixation of 4-Part Proximal Humerus Fractures and Fracture Dislocations Using Extended Deltoid-splitting Approach, Locking Plates, and Calcium Sulfate Graft: Technical Details

Surgical treatment of 4-part proximal humerus fractures and fracture dislocations remain challenging because of difficulties in exposure, reduction, and achieving a stable internal fixation. We have treated these injuries using extended deltoid-splitting approach with internal fixation using locking plates, calcium sulfate graft, and tuberosity repair with polyethylene sutures. We have used this technique in 21 cases (20 patients) 7 male, 13 female with displaced 4-part fractures or fracture dislocations. The average age was 59 years (range, 27 to 74 y) and average length of follow-up 5 years (range, 3 to 7 y). Overall 19 cases (90%) achieved good or excellent results. All cases united without any serious complications such as loss of tuberosity fixation, humeral head perforation, avascular necrosis, or axillary nerve palsy. In 1 case there was varus malunion. In another varus malunion and infection, but this resolved satisfactorily with 1 episode of debridement and insertion of gentamicin-impregnated collagen sheets. The clinical result of both varus malunited cases was good as the tuberosity reconstruction remained anatomic. We have found the extended deltoid-splitting approach to ease exposure, especially in posterior fracture dislocations and enhance accuracy of tuberosity reduction. The use of locking plates, calcium sulfate graft, and tuberosity repair with polyethylene sutures has also given us a reliable means of achieving a stable fixation in these difficult cases, allowing early postoperative rehabilitation.