Hemostatic efficacy of a novel, PEG-coated collagen pad in clinically relevant animal models.

PURPOSE: Currently available hemostatic pads are effective in treating oozing bleeds, but otherwise ineffective in more severe bleeding. This study investigates the hemostatic efficacy of a new hemostatic pad with advanced sealing properties using protein-reactive polyethylene glycol-coated collagen (PCC, Hemopatch) versus an oxidized regenerated cellulose (ORC, Tabotamp/Surgicel Original) in a leporine arterial bleeding model of vascular reconstruction and a porcine hepatic model of general surgery. METHODS: In both models, paired lesions were created and treated according to a randomized scheme and evaluated up to 10 min after application (40 lesions/group/model). Arterial needle holes were created in the femoral arteries of anesthetized rabbits and hepatic lesions were created into hepatic parenchyma of anesthetized pigs. Both models were heparinized to mimic clinical comorbidity. RESULTS: In the leporine vascular surgical model, PCC provided superior hemostatic success compared to ORC at 2 min (Odds Ratio of Success: 85, 95% CI: 25.8-282) and similar hemostatic success at 10 min. In the porcine hepatic model, PCC provided superior hemostatic success compared to ORC at 2 (98 vs 55%, P < 0.001), 3 (93 vs 65%, P < 0.001), 4 (98 vs 68%, P < 0.001) and 5 min (95 vs 80%, P < 0.001), but similar hemostatic success at 8 and 10 min. DISCUSSION: PCC provided 75.4% greater hemostatic success at 2 min in the arterial model and was at least 100 times more likely to be hemostat effective at 2 min in the hepatic model than ORC. CONCLUSIONS: PCC provided faster hemostasis than ORC in a vascular and hepatic surgical model with impaired coagulation.

Swelling, sealing, and hemostatic ability of a novel biomaterial: A polyethylene glycol-coated collagen pad.

Trends in the development of hemostatic agents are towards self-adhering pads. This study investigates a novel biomaterial made of a polyethylene glycol-coated collagen pad (PCC). The swelling and adherence of PCC were investigated in vitro, and the hemostatic and sealing ability was investigated in vivo. In vitro, the maximum swell of PCC submerged in human plasma for 24 h is 65%. The greatest swell was in thickness, averaging 24% to a mean thickness of 2.5 ± 0.19 mm (mean±SD) (N = 20). PCC withstood clinically relevant pressures when applied to a collagen casing washed with bile, lymph, urine, saline, and cerebrospinal fluid mixed at 33% and 67% with blood. In vivo, PCC provided complete hemostasis when applied to severe, arterial bleeds of actively ventilated pulmonary parenchyma at 3, 5, 8, and 10 min after application in a heparinized porcine pulmonary segmentectomy model. The mean rate of bleeding was 17.7 ± 8.6 ml/min. The lungs were ventilated at 15 ± 4 breaths per min and an airway pressure of 19 ± 2 cm H2O. PCC had no incidence of hematoma and an 11% incidence of intraoperative air leak (N = 36). These data are promising for future clinical application of a new versatile, self-adhering hemostatic sealing pad consisting of a polyethylene glycol-coated collagen.

A multidimensional electrophoretic system of separation for the analysis of gene expression (MESSAGE).

Differential gene expression profiling has become of central importance for the analysis of cellular systems at the transcriptional level. By now, many platform technologies including DNA-microarrays, serial analysis of gene expression or RNA-seq have been established in order to facilitate transcriptional profiling. However, these technologies are all subjected to specific limitations, as they require a priori knowledge of annotated genome sequences or are based on substantial bioinformatic infrastructure, for example. As an unbiased alternative we describe here a multidimensional electrophoretic system of separation for the analysis of gene expression for the global transcriptional profiling in any eukaryotic organism. This approach is compatible with standard laboratory equipment comprising high-resolution separation of complex cDNA-probes using two-dimensional DNA-gel electrophoresis. In this context cDNA fragments are separated using non-denaturing PAGE in the first dimension with subsequent denaturing gradient gel electrophoresis in the second dimension. Two-dimensional spot patterns are quantified by well-established bioinformatic algorithms and selected spots are identified using DNA sequencing. Neither does this method necessarily depend on annotated genome sequences, nor does it require sophisticated instrumentation. Strikingly, quantitative data on differential gene expression derived from multidimensional electrophoretic system of separation for the analysis of gene expression highly correlate with corresponding data from quantitative RT-PCR even for transcriptional profiles of limited amounts of total RNA.

CARP, a cardiac ankyrin repeat protein, is up-regulated during wound healing and induces angiogenesis in experimental granulation tissue.

Cardiac ankyrin repeat protein (CARP) was identified by subtractive hybridization as one of a group of genes that are rapidly modulated by acute wounding of mouse skin. Quantitative RT-PCR showed that CARP was strongly induced during the first day after wounding (157.1-fold), and the high level persisted for up to 14 days. Immunohistochemistry and in situ hybridization revealed that CARP was expressed in skeletal muscle, vessel wall, hair follicle, inflammatory cells, and epidermis in the wound area. To examine the effects of CARP on wound healing, we developed an adenoviral CARP vector to treat subcutaneously implanted sponges in either rats or Flk-1(LacZ) knock-in mice. Four days after infection, CARP-infected sponges in rats showed a remarkable increase in the vascular component in granulation tissue as compared to Ad-LacZ controls. This result was confirmed by CD34 immunostaining. By 7 days post-infection of sponge implants in Flk-1(LacZ) knock-in mice, granulation tissue showed many more LacZ-positive cells in Ad-CARP-infected sponges than in virus controls. Ad-CARP treatment also induced neovascularization and increased blood perfusion in rabbit excisional wounds in and ischemic rat wounds. These findings indicate that CARP could play a unique role in therapeutic angiogenesis during wound healing.

Digital analysis of cDNA abundance; expression profiling by means of restriction fragment fingerprinting.

BACKGROUND: Gene expression profiling among different tissues is of paramount interest in various areas of biomedical research. We have developed a novel method (DADA, Digital Analysis of cDNA Abundance), that calculates the relative abundance of genes in cDNA libraries. RESULTS: DADA is based upon multiple restriction fragment length analysis of pools of clones from cDNA libraries and the identification of gene-specific restriction fingerprints in the resulting complex fragment mixtures. A specific cDNA cloning vector had to be constructed that governed missing or incomplete cDNA inserts which would generate misleading fingerprints in standard cloning vectors. Double stranded cDNA was synthesized using an anchored oligo dT primer, uni-directionally inserted into the DADA vector and cDNA libraries were constructed in E. coli. The cDNA fingerprints were generated in a PCR-free procedure that allows for parallel plasmid preparation, labeling, restriction digest and fragment separation of pools of 96 colonies each. This multiplexing significantly enhanced the throughput in comparison to sequence-based methods (e.g. EST approach). The data of the fragment mixtures were integrated into a relational database system and queried with fingerprints experimentally produced by analyzing single colonies. Due to limited predictability of the position of DNA fragments on the polyacrylamid gels of a given size, fingerprints derived solely from cDNA sequences were not accurate enough to be used for the analysis. We applied DADA to the analysis of gene expression profiles in a model for impaired wound healing (treatment of mice with dexamethasone). CONCLUSIONS: The method proved to be capable of identifying pharmacologically relevant target genes that had not been identified by other standard methods routinely used to find differentially expressed genes. Due to the above mentioned limited predictability of the fingerprints, the method was yet tested only with a limited number of experimentally determined fingerprints and was able to detect differences in gene expression of transcripts representing 0.05% of the total mRNA population (e.g. medium abundant gene transcripts).

The healing skin wound: a novel site of action of the chemokine C10.

To gain insight into the molecular mechanisms underlying the wound repair process, we searched for genes that are regulated by skin injury. For this purpose we generated a subtractive cDNA library from normal mouse back skin and 1-day full-thickness excisional wounds. One of the differentially expressed genes encodes the chemokine C10. Using Northern blotting, RNase protection assay and Western blotting, we confirmed the injury-induced expression of C10 at the mRNA and protein level. Maximal levels of C10 mRNA and protein were seen at day 1 after wounding, and expression levels subsequently declined. In situ hybridization and immunohistochemistry revealed expression of C10 in macrophages of the clot and the granulation tissue as well as in keratinocytes of the epidermis and the hair follicles at the wound edge. Since C10 is a potent chemoattractant for macrophages, our results suggest that this chemokine contributes to the strong macrophage influx observed in the healing skin wound.