The use of commercial fibrin glue in dermal replacement material reduces angiogenic and lymphangiogenic gene and protein expression in vitro.

BACKGROUND: Commercial fibrin glue is increasingly finding its way into clinical practice in surgeries to seal anastomosis, and initiate hemostasis or tissue repair. Human biological glue is also being discussed as a possible cell carrier. To date, there are only a few studies addressing the effects of fibrin glue on the cell-molecular level. This study examines the effects of fibrin glue on angiogenesis and lymphangiogenesis, as well as adipose-derived stem cells (ASCs) with a focus on gene and protein expression in scaffolds regularly used for tissue engineering approaches. METHODS: Collagen-based dermal regeneration matrices (DRM) were seeded with human umbilical vein endothelial cells (HUVEC), human dermal lymphatic endothelial cells (LECs), or adipose-derived stem cells (ASC) and fixed with or without fibrin glue according to the experimental group. Cultures were maintained for 1 and 7 days. Finally, angiogenic and lymphangiogenic gene and protein expression were measured with special regard to subtypes of vascular endothelial growth factor (VEGF) and corresponding receptors using Multiplex-qPCR and ELISA assays. In addition, the hypoxia-induced factor 1-alpha (HIF1a) mediated intracellular signaling pathways were included in assessments to analyze a hypoxic encapsulating effect of fibrin polymers. RESULTS: All cell types reacted to fibrin glue application with an alteration of gene and protein expression. In particular, vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor B (VEGFB), vascular endothelial growth factor C (VEGFC), vascular endothelial growth receptor 1 (VEGFR1/FLT1), vascular endothelial growth receptor 2 (VEGFR2/KDR), vascular endothelial growth receptor 3 (VEGFR3/FLT4) and Prospero Homeobox 1 (PROX1) were depressed significantly depending on fibrin glue. Especially short-term fibrin effect led to a continuous downregulation of respective gene and protein expression in HUVECs, LECs, and ASCs. CONCLUSION: Our findings demonstrate the impact of fibrin glue application in dermal regeneration with special regard to angiogenesis and lymphangiogenesis. In particular, a short fibrin treatment of 24 hours led to a decrease in gene and protein levels of LECS, HUVECs, and ASCs. In contrast, the long-term application showed less effect on gene and protein expressions. Therefore, this work demonstrated the negative effects of fibrin-treated cells in tissue engineering approaches and could affect wound healing during dermal regeneration.

A mathematical model of fibrinogen-mediated erythrocyte-erythrocyte adhesion.

Erythrocytes are deformable cells that undergo progressive biophysical and biochemical changes affecting the normal blood flow. Fibrinogen, one of the most abundant plasma proteins, is a primary determinant for changes in haemorheological properties, and a major independent risk factor for cardiovascular diseases. In this study, the adhesion between human erythrocytes is measured by atomic force microscopy (AFM) and its effect observed by micropipette aspiration technique, in the absence and presence of fibrinogen. These experimental data are then used in the development of a mathematical model to examine the biomedical relevant interaction between two erythrocytes. Our designed mathematical model is able to explore the erythrocyte-erythrocyte adhesion forces and changes in erythrocyte morphology. AFM erythrocyte-erythrocyte adhesion data show that the work and detachment force necessary to overcome the adhesion between two erythrocytes increase in the presence of fibrinogen. The changes in erythrocyte morphology, the strong cell-cell adhesion and the slow separation of the two cells are successfully followed in the mathematical simulation. Erythrocyte-erythrocyte adhesion forces and energies are quantified and matched with experimental data. The changes observed on erythrocyte-erythrocyte interactions may give important insights about the pathophysiological relevance of fibrinogen and erythrocyte aggregation in hindering microcirculatory blood flow.

Fibrin glue as a local drug and photosensitizer delivery system for photochemical internalization: Potential for bypassing the blood-brain barrier.

BACKGROUND: Chemotherapy has had disappointing results in the treatment of glioblastoma multiforme (GBM). This is in part due to limited systemic drug penetration through the blood-brain barrier. This limitation can be overcome by implantation of drug-loaded hydrogels, such as fibrin glue (FG), directly into the tumor resection cavity. Photochemical internalization (PCI) has been shown to enhance the efficacy of a large number of chemotherapeutic agents, including bleomycin (BLM). This study examined the ability of loaded FG to release BLM and photosensitizer to enable PCI-induced growth inhibition of glioma spheroids in vitro. MATERIALS AND METHODS: FG layers, loaded with drug and photosensitizer, were formed in wells of a 24-well plate. Supernatants covering the FG layers were harvested after 48 h. F98 glioma spheroids were co-incubated with harvested supernatants for 24 h, followed by light exposure. Spheroid growth was monitored for an additional 14 days. RESULTS: 100% of the drug bleomycin and 90% of the photosensitizer (AlPcS2a) was released from the FG over a 48 h interval. Spheroid growth was significantly inhibited or completely suppressed by PCI of released drug and photosensitizer in many of the concentration combinations tested. PCI-induced growth inhibition increased with increasing light levels. CONCLUSIONS: The results demonstrate that both drug and photosensitizer were loaded into and released in a non-degraded form for an extended time period. The growth inhibition caused by FG-released BLM was significantly enhanced by FG-released AlPcS2a-mediated PCI.

[Therapeutic effect of amniotic membrane-fibrin sealant cement on severe ocular surface alkali burn in rabbits].

Objective To prepare a biologically active amniotic membrane powder and explore its preservation conditions, and to evaluate the efficacy of the amniotic membrane (AM)-fibrin sealant (FS) cement made from the amniotic powder on the rabbit severe ocular surface alkali burn model. Methods Experimental research. Fresh AM was air-dried, cooled with liquid nitrogen, ground into amniotic powder and sterilized by radiation. The expression of transformed growth factor, nerve growth factor receptor (NGFR), hepatocyte growth factor (HGF), epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) after preparation and 10, 20 and 30 days after storage at room temperature, 4 ℃ and -20 ℃ was tested and compared with that in the fresh AM. The AM-FS cement containing different concentrations of amniotic powder and no amniotic powder was diluted. Rabbit corneal epithelial cells were cultured for 72 hours. The effects of different concentrations of amniotic powder on epithelial cell growth were observed by light microscopy, and the amniotic powder concentration with the largest absorbance value at 450 nm was selected for subsequent animal experiments. Thirty-two right eyes of 32 rabbits as the severe ocular surface alkali burn model were divided using the random counting method into the AM-FS cement group, fresh AM transplantation group, FS group and antibiotic control group (8 rabbits each group) and given different interventions. After weekly observation of corneal repair, hematoxylin and eosin staining, immunohistochemical staining of monocyte chemotaxis protein 1 (MCP-1)and vascular endothelial growth factor (VEGF) were performed and detected by light microscopy at 28 days. The logFC values of the growth factor or receptor expression difference ratio were corrected by BH; the data were analyzed by t-test and analysis of variance. Results: The expression of TGF in the amniotic membrane powder compared with the fresh amniotic membrane group (logFC=-0.11), and the expression of NGFR (HGF, EGF, bFGF) was higher than that of the fresh amniotic membrane group (logFC=-2.07, 0.72, 0.46, 2.62; P<0.05); the expression of HGF, bFGF and EGF in amniotic membrane powder stored for 10 days and 20 days were no lower than fresh amniotic membrane; at 30 days, the expression of growth factors or receptors except HGF and bFGF were decreased, and HGF, bFGF and EGF were no less than 4 ℃ and -20 ℃.The maximum A value was obtained for 0.25 mg/ml of the amniotic membrane powder after 72 hours of the CEC culture 0.98±0.05. The corneal recovery was better in the AM-FS and fresh amniotic membrane transplant groups, with corneal turbidity scores of 3.75±0.46 and 3.50±0.46, respectively, on 28 days, lower than antibiotics (4.29±0.45) (t=2.480, 3.629; P=0.019, 0.001). The corneal neovascular area in the antibiotic control group was compared with the other three groups (t=4.040, 4.339, 2.820; all P<0.001); the corneal neovascular area in the AM-FS group was (9.88±0.20) and (18.96±0.18) mm2 at 7 and 28 days. The corneal neovascularization area at 7 and 28 days in the fresh AM group [(9.54±0.22) and (18.08±0.96) mm2] was smaller than the AM-FS group (t=3.085, 3.017, P=0.005, 0.005). Despite the tiny statistical difference (0.34, 0.88), there was no clinical difference. Hematoxylin and eosin staining showed corneal structures were intact in the AM-FS and fresh AM groups, the epithelial arrangement became normal, and the corneal healing was superior to the FS and antibiotic control groups. Immunohistochemistry showed that the positive expression of VEGF in the fresh AM group was weaker than that in the remaining three groups. MCP-1 was expressed to a similar extent in the AM-FS and fresh AM groups. Conclusions: The active cytokine had high expression and stable properties at room temperature. The AM-FS cement containing 0.25 mg/ml amniotic powder can promote the repair of corneal epithelium, reduce inflammatory reaction and corneal neovascularization after alkali burning in rabbit eyes.

Fibrin glue does not assist migration and proliferation of chondrocytes in collagenic membranes: an in vitro study.

BACKGROUND: Some authors secured the membrane during matrix-induced autologous chondrocyte implantation (mACI) with fibrin glue or did not use a formal fixation. The real impact of fibrin glue addition on chondrocytes migration and proliferation has not yet been clarified. This study evaluated the impact of fibrin glue on a chondrocyte loaded collagenic membrane. METHODS: A resorbable collagen I/III porcine derived membrane commonly employed in AMIC was used for all experiments. Chondrocytes from three difference donors were used. At 1-, 2-, 3-, 4-, 6-, and at 8-week the membranes were embedded in Mounting Medium with Dapi (ABCAM, Cambridge, UK). The Dapi contained in the mounting medium ties the DNA of the cell nucleus and emits a blue fluorescence. In this way, the spreading of the cells in the membrane can be easily monitored. The outcomes of interest were to evaluate (1) cell migration and (2) cell proliferation within the porous membrane layer. DAPI/nuclei signals were analysed with fluorescence microscope under a magnification of 100-fold. RESULTS: The no-fibrin group demonstrated greater migration of the cells within the membrane. Although migration resulted higher in the no-fibrin group at every follow-up, this difference was significant only at week 1 (P < 0.001), 2 (P = 0.004), and 3 (P = 0.03). No difference was found at week 3, 6, and 8. The no-fibrin group demonstrated greater proliferation of the chondrocytes within the membrane. These differences were significant at week 4 (P < 0.0001), 6 (P < 0.0001), 8 (P < 0.0001). CONCLUSION: The use of fibrin glue over a resorbable membrane leads to lower in vitro proliferation and migration of chondrocytes.

Fibrin glue as a local drug-delivery system for bacteriophage PA5.

Fibrin glue has been used clinically for decades in a wide variety of surgical specialties and is now being investigated as a medium for local, prolonged drug delivery. Effective local delivery of antibacterial substances is important perioperatively in patients with implanted medical devices or postoperatively for deep wounds. However, prolonged local application of antibiotics is often not possible or simply inadequate. Biofilm formation and antibiotic resistance are also major obstacles to antibacterial therapy. In this paper we test the biocompatibility of bacteriophages incorporated within fibrin glue, track the release of bacteriophages from fibrin scaffolds, and measure the antibacterial activity of released bacteriophages. Fibrin glue polymerized in the presence of the PA5 bacteriophage released high titers of bacteriophages during 11 days of incubation in liquid medium. Released PA5 bacteriophages were effective in killing Pseudomonas aeruginosa PA01. Overall, our results show that fibrin glue can be used for sustained delivery of bacteriophages and this strategy holds promise for many antibacterial applications.

Nano-hydroxy apatite/chitosan/gelatin scaffolds enriched by a combination of platelet-rich plasma and fibrin glue enhance proliferation and differentiation of seeded human dental pulp stem cells.

The purpose of this study was to investigate the effects of Fibrin Glue (FG) and activated platelet-rich plasma (a-PRP) on the proliferation and osteogenic differentiation of human dental pulp stem cells (h-DPSCs). Therefore, we planned to investigate in vitro behavior of porous composite scaffolds based on chitosan-gelatin/nanohydroxyapatite (CS-G/nHA) treated with FG and a-PRP. The porous structure of CS-G/nHA was prepared using combination of particle leaching and freeze-drying methods. The a-PRP was prepared from the centrifugation of whole blood activated with calcium chloride. Four groups of composite scaffolds were fabricated to seed h-DPSCs: (1) a-PRP-FG/CS-G/nHA; (2) FG/CS-G/nHA; (3) a-PRP/CS-G/nHA; (4) CS-G/nHA. The 14 days SEM image reveled organized fibrin network on scaffolds surface. All groups treated with FG and a-PRP, showed improved adhesion of seeded h-DPSCs compared to CS-G/nHA. Cytotoxicity of the composite scaffolds was assessed by MTT. Alizarin red staining confirmed the formation of bone minerals by h-DPSCs after 21 days of cell seeding. In addition, the a-PRP-FG treated scaffolds exhibited significantly elevated bone gamma-carboxyglutamic acid-containing protein (BGLAP), bone morphogenetic protein 2 (BMP2), and runt-related transcription factor 2 (RUNX2) gene expression. The present result the composite scaffolds treated with FG and a-PRP showed a fibrin network, preferentially on the surface of composite scaffold increasing the mineralization and osteoblastic differentiation of harvested cells. In addition, a-PRP-FG/ CS-G/nHA scaffold increased bone marker gene expressions from day 7 to day 21.

Direct Spinal Ventral Root Repair following Avulsion: Effectiveness of a New Heterologous Fibrin Sealant on Motoneuron Survival and Regeneration.

Axonal injuries at the interface between central and peripheral nervous system, such as ventral root avulsion (VRA), induce important degenerative processes, mostly resulting in neuronal and motor function loss. In the present work, we have compared two different fibrin sealants, one derived from human blood and another derived from animal blood and Crotalus durissus terrificus venom, as a promising treatment for this type of injury. Lewis rats were submitted to VRA (L4-L6) and had the avulsed roots reimplanted to the surface of the spinal cord, with the aid of fibrin sealant. The spinal cords were processed to evaluate neuronal survival, synaptic stability, and glial reactivity, 4 and 12 weeks after lesion. Sciatic nerves were processed to investigate Schwann cell activity by p75(NTR) expression (4 weeks after surgery) and to count myelinated axons and morphometric evaluation (12 weeks after surgery). Walking track test was used to evaluate gait recovery, up to 12 weeks. The results indicate that both fibrin sealants are similarly efficient. However, the snake-derived fibrin glue is a potentially safer alternative for being a biological and biodegradable product which does not contain human blood derivatives. Therefore, the venom glue can be a useful tool for the scientific community due to its advantages and variety of applications.

TSG-6 mediates the effect of tendon derived stem cells for rotator cuff healing.

BACKGROUND: Bone marrow stem cells (MSCs) were able to reduce fibrovascular tissues formation via TNF alpha-stimulated gene/protein 6 (6TSG-6) in various animal models. At the same time, tendon-derived stem cells (TDSCs) were able to promote rotator cuff healing; however, the mechanism is still unknown. AIM: To investigate the role of TSG-6 in the treatment of rotator cuff healing with TDSCs. MATERIALS AND METHODS: 45 rats underwent unilateral detachment and repair of the supraspinatus tendon. 15 animals received TDSCs in a fibrin glue carrier(Group A), 15 received TSG-6 silenced TDSCs (Group B), and 15 received fibrin glue for control (Group C). Animals were sacrificed at 4 weeks and evaluated for the biomechanical testing. Statistical analysis was performed with an independent t test with significance set at p = 0.05. RESULTS: The ultimate stress was greater in the TDSCs group (4.91 ± 1.41 N/mm(2)) as compared with the Control group (2.99 ± 1.04 N/mm(2)) (p < 0.05). However, when silent the expression of TSG-6, the TSG-6 silenced group (3.36 ± 0.96 N/mm(2)) showed no benefit over the control group (p = 0.32). CONCLUSIONS: TSG-6 mediates the function of TDSCs to improve the structure and the attachment strength of the healing tendon-bone interface.

In vitro effects of proteases in human pancreatic juice on stability of liquid and carrier-bound fibrin sealants.

BACKGROUND: Fibrin sealants are used in pancreatic surgery to prevent leakage of pancreatic fluid and reduce associated complications. The efficacy of this approach is unclear. METHODS: Fibrin clots were generated in vitro from two commercially available liquid fibrin sealants (Tissucol Duo® and Evicel®) and the carrier-bound fibrin sealant Tachosil®, and exposed to normal saline or human pancreatic fluid. Stability of the sealants was assessed by release of the fibrin and collagen degradation products, D-dimer and hydroxyproline. The effect of protease inhibitors on sealant breakdown was assessed. RESULTS: Clots generated from liquid fibrin sealants degraded rapidly in pancreatic fluid, but not in normal saline. D-dimer release from fibrin clots by pancreatic fluid was approximately 1700 µg/ml after 24 h and less than 20 µg/ml by saline. Pancreatic fluid, but not normal saline, degraded both the fibrin and collagen component of Tachosil®. After 6 h, mean(s.e.m.) D-dimer levels in pancreatic fluid exposed to Tachosil® were 850(183) ng/ml, compared with 60(6) ng/ml in normal saline. The mean(s.e.m.) hydroxyproline concentration in pancreatic fluid was 497(17) µg/ml after a 24-h exposure to Tachosil®, compared with 26(12) µg/ml in normal saline. Protease inhibitors significantly inhibited breakdown of liquid sealants (D-dimer levels less than 50 µg/ml after 24 h) and Tachosil® (D-dimer release 179(12) ng/ml at 6 h; hydroxyproline release 181(29) µg/ml at 24 h). CONCLUSION: Proteases in pancreatic juice effectively degrade both liquid and carrier-bound fibrin sealants in vitro. The use of these products in pancreatic surgery with the aim of preventing leakage of pancreatic fluid is not supported by this experimental study.

Is the use of autologous platelet-rich plasma gels in gynecologic, cardiac, and general, reconstructive surgery beneficial?

Tissue repair at wound sites begins with clot formation, and subsequently platelet degranulation with the release of platelet growth factors, which are necessary and well-regulated processes to achieve wound healing. Platelet-derived growth factors are biologically active substances that enhance tissue repair mechanisms, such as chemotaxis, cell proliferation, angiogenesis, extracellular matrix deposition, and remodeling. This review describes the biological background and results on the topical use of autologous platelet-rich plasma and platelet gel in gynecologic, cardiac, and general surgical procedures, including chronic wound management and soft-tissue injuries.

In search of a consensus terminology in the field of platelet concentrates for surgical use: platelet-rich plasma (PRP), platelet-rich fibrin (PRF), fibrin gel polymerization and leukocytes.

In the field of platelet concentrates for surgical use, most products are termed Platelet-Rich Plasma (PRP). Unfortunately, this term is very general and incomplete, leading to many confusions in the scientific database. In this article, a panel of experts discusses this issue and proposes an accurate and simple terminology system for platelet concentrates for surgical use. Four main categories of products can be easily defined, depending on their leukocyte content and fibrin architecture: Pure Platelet-Rich Plasma (P-PRP), such as cell separator PRP, Vivostat PRF or Anitua's PRGF; Leukocyteand Platelet-Rich Plasma (L-PRP), such as Curasan, Regen, Plateltex, SmartPReP, PCCS, Magellan, Angel or GPS PRP; Pure Plaletet-Rich Fibrin (P-PRF), such as Fibrinet; and Leukocyte- and Platelet-Rich Fibrin (L-PRF), such as Choukroun's PRF. P-PRP and L-PRP refer to the unactivated liquid form of these products, their activated versions being respectively named P-PRP gels and L-PRP gels. The purpose of this search for a terminology consensus is to plead for a more serious characterization of these products. Researchers have to be aware of the complex nature of these living biomaterials, in order to avoid misunderstandings and erroneous conclusions. Understanding the biomaterials or believing in the magic of growth factors ? From this choice depends the future of the field.

Platelet-rich plasma (PRP) and Platelet-Rich Fibrin (PRF): surgical adjuvants, preparations for in situ regenerative medicine and tools for tissue engineering.

The recent developement of platelet concentrate for surgical use is an evolution of the fibrin glue technologies used since many years. The initial concept of these autologous preparations was to concentrate platelets and their growth factors in a plasma solution, and to activate it into a fibrin gel on a surgical site, in order to improve local healing. These platelet suspensions were often called Platelet-Rich Plasma (PRP) like the platelet concentrate used in transfusion medicine, but many different technologies have in fact been developed; some of them are even no more platelet suspensions, but solid fibrin-based biomaterials called Platelet-Rich Fibrin (PRF). These various technologies were tested in many different clinical fields, particularly oral and maxillofacial surgery, Ear-Nose-Throat surgery, plastic surgery, orthopaedic surgery, sports medicine, gynecologic and cardiovascular surgery and ophthalmology. This field of research unfortunately suffers from the lack of a proper accurate terminology and the associated misunderstandings, and the literature on the topic is quite contradictory. Indeed, the effects of these preparations cannot be limited to their growth factor content: these products associate many actors of healing in synergy, such as leukocytes, fibrin matrix, and circulating progenitor cells, and are in fact as complex as blood itself. If platelet concentrates were first used as surgical adjuvants for the stimulation of healing (as fibrin glues enriched with growth factors), many applications for in situ regenerative medicine and tissue engineering were developed and offer a great potential. However, the future of this field is first dependent on his coherence and scientific clarity. The objectives of this article is to introduce the main definitions, problematics and perspectives that are described in this special issue of Current Pharmaceutical Biotechnology about platelet concentrates.

Fibrin glue is a candidate scaffold for long-term therapeutic protein expression in spontaneously differentiated adipocytes in vitro.

Adipose tissue is expected to provide a source of cells for protein replacement therapies via auto-transplantation. However, the conditioning of the environment surrounding the transplanted adipocytes for their long-term survival and protein secretion properties has not been established. We have recently developed a preparation procedure for preadipocytes, ceiling culture-derived proliferative adipocytes (ccdPAs), as a therapeutic gene vehicle suitable for stable gene product secretion. We herein report the results of our evaluation of using fibrin glue as a scaffold for the transplanted ccdPAs for the expression of a transduced gene in a three-dimensional culture system. The ccdPAs secreted the functional protein translated from an exogenously transduced gene, as well as physiological adipocyte proteins, and the long viability of ccdPAs (up to 84 days) was dependent on the fibrinogen concentrations. The ccdPAs spontaneously accumulated lipid droplets, and their expression levels of the transduced exogenous gene with its product were maintained for at least 56 days. The fibrinogen concentration modified the adipogenic differentiation of ccdPAs and their exogenous gene expression levels, and the levels of exogenously transduced gene expression at the different fibrinogen concentrations were dependent on the extent of adipogenic differentiation in the gel. These results indicate that fibrin glue helps to maintain the high adipogenic potential of cultured adipocytes after passaging in a 3D culture system, and suggests that once they are successfully implanted at the transplantation site, the cells exhibit increased expression of the transduced gene with adipogenic differentiation.

Effects of fibrin, thrombin, and blood on breast capsule formation in a preclinical model.

BACKGROUND: The root cause of capsular contracture (CC) associated with breast implants is unknown. Recent evidence points to the possible role of fibrin and bacteria in CC formation. OBJECTIVES: The authors sought to determine whether fibrin, thrombin, and blood modulated the histological and microbiological outcomes of breast implant capsule formation in a rabbit model. METHODS: The authors carried out a case-control study to assess the influence of fibrin, thrombin, and blood on capsule wound healing in a rabbit model. Eighteen New Zealand white rabbits received four tissue expanders. One expander acted as a control, whereas the other expander pockets received one of the following: fibrin glue, rabbit blood, or thrombin sealant. Intracapsular pressure/volume curves were compared among the groups, and histological and microbiological evaluations were performed (capsules, tissue expanders, rabbit skin, and air). The rabbits were euthanized at two or four weeks. RESULTS: At four weeks, the fibrin and thrombin expanders demonstrated significantly decreased intracapsular pressure compared to the control group. In the control and fibrin groups, mixed inflammation correlated with decreased intracapsular pressure, whereas mononuclear inflammation correlated with increased intracapsular pressure. The predominant isolate in the capsules, tissue expanders, and rabbit skin was coagulase-negative staphylococci. For fibrin and thrombin, both cultures that showed an organism other than staphylococci and cultures that were negative were associated with decreased intracapsular pressure, whereas cultures positive for staphylococci were associated with increased intracapsular pressure. CONCLUSIONS: Fibrin application during breast implantation may reduce rates of CC, but the presence of staphylococci is associated with increased capsule pressure even in the presence of fibrin, so care should be taken to avoid bacterial contamination.

Fibrin glue: a scaffold for cellular-based therapy in a critical-sized defect.

PURPOSE: Cartilage-based treatments have vast applications in plastic and reconstructive surgery, especially craniofacial constructs. Current techniques in craniofacial cartilage reconstructions greatly rely on autologous donor site harvest. Whole cartilage grafts are wrought with complications of warping, resorption, extrusion, and donor site morbidity. Percutaneous delivery of expanded chondrocytes would have the potential to expand a small quantity of autologous cells to deliver cell therapy. To deliver chondrocytes effectively, there must be a reliable medium in which chondrocytes can be kept. The purpose of this work is to highlight the utility of fibrin glue sealant, Evicel, as a suitable chondrocyte carrier in the treatment of a critical-sized defect model of nonarticular cartilage previously developed in our laboratory. METHODS: Athymic rats were separated into 2 groups: fibrin glue (n = 3) and fibrin glue + rat chondrocytes (n = 6). The animals with an empty defect were used to ensure that they responded normally to the procedure. All animals received a 3-mm full-thickness xiphoid cartilage defect characterized previously as a critical-sized defect in our laboratory (Moyer HR, Wang Y, Farooque T, et al. Tissue Eng Part A. 2010;16:2321-2330). A control animal received no xiphoid defect creation procedure. The fibrin glue group was treated with 0.5 mL of fibrin glue placed directly into the 3-mm defect. The fibrin glue/rat chondrocyte group received a mixture of 1 × 10 resting zone chondrocytes mixed with 0.5 mL of fibrin glue. Rats were euthanized at 5 weeks (35 days) and their xiphoid cartilages harvested. The xiphoids were analyzed with morphometrics through histology and microcomputed tomography. RESULTS: In the fibrin glue vehicle group, there was minimal evidence of wound healing. Xiphoid defects treated with resting zone chondrocytes in a fibrin glue carrier were significantly smaller (P = 0.002) at harvest and had significantly more glycosaminoglycan content on microcomputed tomography analysis. Thus, there was significant healing in the chondrocyte/fibrin glue group. CONCLUSION: Human fibrin sealant is an effective chondrocyte carrier and retains viable cells. Treatment of a nonarticular critical-size defect with resting zone chondrocytes embedded in a fibrin glue polymer demonstrates tissue healing.

Cell compatibility of fibrin sealants: in vitro study with cells involved in soft tissue repair.

Fibrin sealants can be used to support tissue regeneration or as vehicles for delivery of cells in tissue engineering. Differences in the composition of fibrin sealants, however, could determine the success of such applications. The results presented in this article show clear differences between Fibrin sealant A (FS A) clots and Fibrin sealant B (FS B) clots with respect to their compatibility with primary human cells involved in soft tissue repair. FS A clots, which are characterized by a physiological coarse fibrin structure, promoted attachment, spreading, and proliferation of keratinocytes, fibroblasts, and endothelial cells. In contrast, FS B clots displaying a fine to medium clot structure failed to support spreading of all three cell types. Adhesion of keratinocytes was decreased on FS B clots compared to FS A clots after 3 h incubation, whereas number of attached fibroblasts and endothelial cells was initially comparable between the two fibrin sealants. However, all three cell types proliferated on FS A clots but no sustained proliferation was detected on FS B clots. We further demonstrate that the observed differences between FS A and B clots are partly based upon 1 M sodium chloride extractable constituents, like thrombin, and partly on nonextractable constituents or the fibrin structure. In conclusion, our in vitro results demonstrate that FS A clots serve as a provisional matrix that encourages adhesion and growth of keratinocytes, fibroblasts, and endothelial cells. Therefore, FS A seems to be well suited for applications in tissue engineering.

Enhancement of capillary and cellular ingrowth in ePTFE implants with a proangiogenic recombinant construct derived from fibronectin.

Based on our discoveries of a unique, synergistic interplay between vascular endothelial growth factor (VEGF) and specific domains of the matrix protein fibronectin (FN), we used recombinant technology to create a new protein construct derived from the cell-binding and VEGF-binding domains of FN. We wished to test the hypothesis that this prototype recombinant FN (rFN) protein would enhance cellular and capillary ingrowth in vivo into expanded polytetrafluoroethylene (ePTFE) implants. ePTFE disks of high porosity (60 micron internodal distance) were embedded with fibrin gel and heparin, with/without mixtures of VEGF and rFN and were implanted subcutaneously in rats. Control implants embedded with fibrin glue and heparin alone showed an average of 8.5% (±0.51% standard error mean (SEM)) cellular ingrowth. The addition of either VEGF or rFN caused a modest but significant increase in cellular ingrowth (12.7 ± 1% and 11.8 ± 0.98%, respectively, p < 0.004). However, the combination of rFN/VEGF/heparin dramatically increased cellular ingrowth (27.6 ± 1.62%, p < 0.001), compared with all other treatments. Quantification of capillary ingrowth yielded the same pattern. These results suggest that the incorporation of such biological modulators into cardiovascular implants could offer new strategies for the design of a ready-made small diameter prosthetic graft with enhanced capacity for neovascularization and endothelialization.