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Development of Optimized Tissue-Factor-Targeted Peptide Amphiphile Nanofibers to Slow Noncompressible Torso Hemorrhage.

ABSTRACT: Noncompressible torso hemorrhage accounts for a significant portion of preventable trauma deaths. We report here on the development of injectable, targeted supramolecular nanotherapeutics based on peptide amphiphile (PA) molecules that are designed to target tissue factor (TF) and, therefore, selectively localize to sites of injury to slow hemorrhage. Eight TF-targeting sequences were identified, synthesized into PA molecules, coassembled with nontargeted backbone PA at various weight percentages, and characterized via circular dichroism spectroscopy, transmission electron microscopy, and X-ray scattering. Following intravenous injection in a rat liver hemorrhage model, two of these PA nanofiber coassemblies exhibited the most specific localization to the site of injury compared to controls (p < 0.05), as quantified using immunofluorescence imaging of injured liver and uninjured organs. To determine if the nanofibers were targeting TF in vivo, a mouse saphenous vein laser injury model was performed and showed that TF-targeted nanofibers colocalized with fibrin, demonstrating increased levels of nanofiber at TF-rich sites. Thromboelastograms obtained using samples of heparinized rat whole blood containing TF demonstrated that no clots were formed in the absence of TF-targeted nanofibers. Lastly, both PA nanofiber coassemblies decreased blood loss in comparison to sham and backbone nanofiber controls by 35-59% (p < 0.05). These data demonstrate an optimal TF-targeted nanofiber that localizes selectively to sites of injury and TF exposure, and, interestingly, reduces blood loss. This research represents a promising initial phase in the development of a TF-targeted injectable therapeutic to reduce preventable deaths from hemorrhage.

SUBMITTER: Klein MK

PROVIDER: S-EPMC7587470 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Rational development of technology for rapid control of noncompressible torso hemorrhage (NCTH) requires detailed understanding of what is bleeding. Our objectives were to describe the anatomic location of truncal bleeding in patients presenting with NCTH and compare endovascular (ENDO) management versus open (OPEN) management. METHODS:This is a retrospective study of adult trauma patients with NCTH admitted to four urban Level I trauma centers in the Houston and San Antonio metropolitan areas in 2008 to 2012. Inclusion criteria include named axial torso vessel disruption, Abbreviated Injury Scale chest or abdomen score of 3 or higher with shock (base excess, <-4) or truncal operation in 90 minutes or less, or pelvic fracture with ring disruption. Exclusion criteria include isolated hip fractures, falls from standing, or prehospital cardiopulmonary resuscitation. After dichotomizing into OPEN, ENDO, and resuscitative thoracotomy (RT) groups based on the initial approach to control NCTH, a mixed-effects Poisson regression with robust error variance (controlling for age, mechanism, Injury Severity Score, shock, hypotension, and severe head injury as fixed effects and site as a random effect) was used to test the hypothesis that ENDO was associated with reduced in-hospital mortality in NCTH patients. RESULTS:Five hundred forty-three patients with NCTH underwent ENDO (n = 166, 31%), OPEN (n = 309, 57%), or RT (n = 68, 12%). Anatomic bleeding locations were 25% chest, 41% abdomen, and 31% pelvis. ENDO was used to treat relatively few types of vascular injuries, whereas OPEN and RT injuries were more diverse. ENDO patients had more blunt trauma (95% vs. 34% vs. 32%); severe injuries (median Injury Severity Score, 34 vs. 27 vs. 21), and increased time to intervention (median, 298 vs. 92 vs. 51 minutes) compared with OPEN and RT. Mortality was 15% versus 20% versus 79%. ENDO was associated with decreased mortality compared to OPEN (relative risk, 0.58; 95% confidence interval, 0.46-0.73). CONCLUSION:Although ENDO may reduce mortality in NCTH patients, significant group differences limit the generalizability of this finding. LEVEL OF EVIDENCE:Therapeutic, level V.

Project description:Peripheral nerve injuries can result in lifelong disability. Primary coaptation is the treatment of choice when the gap between transected nerve ends is short. Long nerve gaps seen in more complex injuries often require autologous nerve grafts or nerve conduits implemented into the repair. Nerve grafts, however, cause morbidity and functional loss at donor sites, which are limited in number. Nerve conduits, in turn, lack an internal scaffold to support and guide axonal regeneration, resulting in decreased efficacy over longer nerve gap lengths. By comparison, peptide amphiphiles (PAs) are molecules that can self-assemble into nanofibers, which can be aligned to mimic the native architecture of peripheral nerve. As such, they represent a potential substrate for use in a bioengineered nerve graft substitute. To examine this, we cultured Schwann cells with bioactive PAs (RGDS-PA, IKVAV-PA) to determine their ability to attach to and proliferate within the biomaterial. Next, we devised a PA construct for use in a peripheral nerve critical sized defect model. Rat sciatic nerve defects were created and reconstructed with autologous nerve, PLGA conduits filled with various forms of aligned PAs, or left unrepaired. Motor and sensory recovery were determined and compared among groups. Our results demonstrate that Schwann cells are able to adhere to and proliferate in aligned PA gels, with greater efficacy in bioactive PAs compared to the backbone-PA alone. In vivo testing revealed recovery of motor and sensory function in animals treated with conduit/PA constructs comparable to animals treated with autologous nerve grafts. Functional recovery in conduit/PA and autologous graft groups was significantly faster than in animals treated with empty PLGA conduits. Histological examinations also demonstrated increased axonal and Schwann cell regeneration within the reconstructed nerve gap in animals treated with conduit/PA constructs. These results indicate that PA nanofibers may represent a promising biomaterial for use in bioengineered peripheral nerve repair.

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Development of Optimized Tissue-Factor-Targeted Peptide Amphiphile Nanofibers to Slow Noncompressible Torso Hemorrhage.

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