Bone Morphogenetic Protein-2 Adsorption onto Poly-ɛ-caprolactone Better Preserves Bioactivity In Vitro and Produces More Bone In Vivo than Conjugation Under Clinically Relevant Loading Scenarios

Background: One strategy to reconstruct large bone defects is to prefabricate a vascularized flap by implanting a biomaterial scaffold with associated biologics into the latissimus dorsi and then transplanting this construct to the defect site after a maturation period. This strategy, similar to all clinically and regulatory feasible biologic approaches to surgical reconstruction, requires the ability to quickly (<1?h within an operating room) and efficiently bind biologics to scaffolds. It also requires the ability to localize biologic delivery. In this study, we investigated the efficacy of binding bone morphogenetic protein-2 (BMP2) to poly-?-caprolactone (PCL) using adsorption and conjugation as a function of time. Methods: BMP2 was adsorbed (Ads) or conjugated (Conj) to PCL scaffolds with the same three-dimensional printed architecture while altering exposure time (0.5, 1, 5, and 16?h), temperature (4°C, 23°C), and BMP2 concentration (1.4, 5, 20, and 65??g/mL). The in vitro release was quantified, and C2C12 cell alkaline phosphatase (ALP) expression was used to confirm bioactivity. Scaffolds with either 65 or 20??g/mL Ads or Conj BMP2 for 1?h at 23°C were implanted subcutaneously in mice to evaluate in vivo bone regeneration. Micro-computed tomography, compression testing, and histology were performed to characterize bone regeneration. Results: After 1?h exposure to 65??g/mL BMP2 at 23°C, Conj and Ads resulted in 12.83±1.78 and 10.78±1.49??g BMP2 attached, respectively. Adsorption resulted in a positive ALP response and had a small burst release; whereas conjugation provided a sustained release with negligible ALP production, indicating that the conjugated BMP2 may not be bioavailable. Adsorbed 65??g/mL BMP2 solution resulted in the greatest regenerated bone volume (15.0±3.0?mm3), elastic modulus (20.1±3.0?MPa), and %bone ingrowth in the scaffold interior (17.2%±5.4%) when compared with conjugation. Conclusion: Adsorption may be optimal for the clinical application of prefabricating bone flaps due to BMP2 binding in a short exposure time, retained BMP2 bioactivity, and bone growth adhering to scaffold geometry and into pores with healthy marrow development.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140249/1/ten.tec.2014.0377.pd

Biomechanical evaluation of human and porcine Auricular cartilage

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112214/1/lary25040.pd

Image-Based, Fiber Guiding Scaffolds: A Platform for Regenerating Tissue Interfaces

In the oral and craniofacial complex, tooth loss is the most commonly acquired disfiguring injury. Among the most formidable challenges of reconstructing tooth-supporting osseous defects in the oral cavity is the regeneration of functional multi-tissue complexes involving bone, ligament, and tooth cementum. Furthermore, periodontal multi-tissue engineering with spatiotemporal orientation of the periodontal ligament (PDL) remains the most challenging obstacle for restoration of physiological loading and homeostasis. We report on the ability of a hybrid computer-designed scaffold?developed utilizing computed tomography?to predictably facilitate the regeneration and integration of dental supporting tissues. Here, we provide the protocol for rapid prototyping, manufacture, surgical implantation, and evaluation of dual-architecture scaffolds for controlling fiber orientation and facilitating morphogenesis of bone-ligament complexes. In contrast to conventional single-system methods of fibrous tissue formation, our protocol supports rigorous control of multi-compartmental scaffold architecture using computational scaffold design and manufacturing by 3D printing, as well as the evaluation of newly regenerated tissue physiology for clinical implementation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140247/1/ten.tec.2013.0619.pd

Contaminants of Emerging Concern in Fish from Western U.S. and Alaskan National Parks — Spatial Distribution and Health Thresholds

Remote national parks of the western U.S. and Alaska are not immune to contaminants of emerging concern. Semivolatile organic compounds (SOCs) such as pesticides and PCBs can selectively deposit from the atmosphere at higher rates in cold, high-elevation and high-latitude sites, potentially increasing risk to these ecosystems. In the environment, SOCs magnify up food chains and are known to increase health risks such as cancer and reproductive impairment. One hundred twenty-eight fish in 8 national parks in Alaska and the western U.S. were analyzed for contaminant concentrations, assessed by region, and compared to human and wildlife health thresholds. SOC concentrations from an additional 133 fish from a previous study were also included, for a total of 31 water bodies sampled. PCBs, endosulfan sulfate, and p,p′-DDE were among the most frequently detected contaminants. Concentrations of historic-use pesticides dieldrin, p,p′-DDE, and/or chlordanes in fish exceeded USEPA guidelines for human subsistence fish consumers and wildlife (kingfisher) health thresholds at 13 of 14 parks. Average concentrations in fish ranged from 0.6-280 ng/g lipid (0.02-7.3 μg/g ww). Contaminant loading was highest in fish from Alaskan and Sierra Nevada parks. Historic compounds were highest in Alaskan parks, while current-use pesticides were higher in the Rockies and Sierra Nevada. This study provides a rigorous analysis of CECs in fish from national parks and identifies regions at potential risk.Keywords: Consumption thresholds, Fish, Semivolatile organic compounds, National park

Rotator Cuff Tendinosis in an Animal Model: Role of Extrinsic and Overuse Factors

The rat shoulder animal model has been used previously to study the role of intrinsic injury (modeled as an acute insult to the tendon), extrinsic injury (modeled as external subacromial impingement), and overuse factors on rotator cuff tendinosis. These studies demonstrated that it is possible to produce rotator cuff tendinosis with any one of these factors in isolation. The current study uses the rat shoulder model to study the roles of extrinsic compression, overuse, and overuse in combination with extrinsic compression, on the development of rotator cuff tendinosis. The results of this study demonstrate that the injury created by overuse plus extrinsic compression is greater than the injuries created by overuse or extrinsic compression alone, particularly when important biomechanical variables are considered. While ineffective in causing a change in supraspinatus tendon properties in animals with normal cage activity, extrinsic compression had a significant and dramatic effect when it was combined with overuse activity. Without an additional factor, such as overhead activity, the extrinsic compression alone may be insufficient to cause tendinosis. The results of the present study support the role of multiple factors in the etiology of some rotator cuff injuries. © 2002 Biomedical Engineering Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44001/1/10439_2004_Article_482753.pd

Dual Delivery of EPO and BMP2 from a Novel Modular Poly-ɛ-Caprolactone Construct to Increase the Bone Formation in Prefabricated Bone Flaps

Poly-?-caprolactone (PCL) is a biocompatible polymer that has mechanical properties suitable for bone tissue engineering; however, it must be integrated with biologics to stimulate bone formation. Bone morphogenetic protein-2 (BMP2) delivered from PCL produces bone when implanted subcutaneously, and erythropoietin (EPO) works synergistically with BMP2. In this study, EPO and BMP2 are adsorbed separately on two 3D-printed PCL scaffold modules that are assembled for codelivery on a single scaffold structure. This assembled modular PCL scaffold with dual BMP2 and EPO delivery was shown to increase bone growth in an ectopic location when compared with BMP2 delivery along a replicate scaffold structure. EPO (200?IU/mL) and BMP2 (65??g/mL) were adsorbed onto the outer and inner portions of a modular scaffold, respectively. Protein binding and release studies were first quantified. Subsequently, EPO+BMP2 and BMP2 scaffolds were implanted subcutaneously in mice for 4 and 8 weeks, and the regenerated bone was analyzed with microcomputed tomography and histology; 8.6±1.4??g BMP2 (22%) and 140±29?IU EPO (69.8%) bound to the scaffold and <1% BMP2 and 83% EPO was released in 7 days. Increased endothelial cell proliferation on EPO-adsorbed PCL discs indicated protein bioactivity. At 4 and 8 weeks, dual BMP2 and EPO delivery regenerated more bone (5.1±1.1 and 5.5±1.6?mm3) than BMP2 alone (3.8±1.1 and 4.3±1.7?mm3). BMP2 and EPO scaffolds had more ingrowth (1.4%±0.6%) in the outer module when compared with BMP2 (0.8%±0.3%) at 4 weeks. Dual delivery produced more dense cellular marrow, while BMP2 had more fatty marrow. Dual EPO and BMP2 delivery is a potential method to regenerate bone faster for prefabricated flaps.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140252/1/ten.tec.2014.0643.pd

SchrlauJillEnvironMolecularToxicologyContaminantsEmergingConcern_SupportingInformation.pdf

Remote national parks of the western U.S. and Alaska are not immune to contaminants of emerging concern. Semivolatile organic compounds (SOCs) such as pesticides and PCBs can selectively deposit from the atmosphere at higher rates in cold, high-elevation and high-latitude sites, potentially increasing risk to these ecosystems. In the environment, SOCs magnify up food chains and are known to increase health risks such as cancer and reproductive impairment. One hundred twenty-eight fish in 8 national parks in Alaska and the western U.S. were analyzed for contaminant concentrations, assessed by region, and compared to human and wildlife health thresholds. SOC concentrations from an additional 133 fish from a previous study were also included, for a total of 31 water bodies sampled. PCBs, endosulfan sulfate, and p,p′-DDE were among the most frequently detected contaminants. Concentrations of historic-use pesticides dieldrin, p,p′-DDE, and/or chlordanes in fish exceeded USEPA guidelines for human subsistence fish consumers and wildlife (kingfisher) health thresholds at 13 of 14 parks. Average concentrations in fish ranged from 0.6-280 ng/g lipid (0.02-7.3 μg/g ww). Contaminant loading was highest in fish from Alaskan and Sierra Nevada parks. Historic compounds were highest in Alaskan parks, while current-use pesticides were higher in the Rockies and Sierra Nevada. This study provides a rigorous analysis of CECs in fish from national parks and identifies regions at potential risk.Keywords: Semivolatile organic compounds, National parks, Consumption thresholds, FishKeywords: Semivolatile organic compounds, National parks, Consumption thresholds, Fis

SchrlauJillEnvironMolecularToxicologyContaminantsEmergingConcern.pdf

Remote national parks of the western U.S. and Alaska are not immune to contaminants of emerging concern. Semivolatile organic compounds (SOCs) such as pesticides and PCBs can selectively deposit from the atmosphere at higher rates in cold, high-elevation and high-latitude sites, potentially increasing risk to these ecosystems. In the environment, SOCs magnify up food chains and are known to increase health risks such as cancer and reproductive impairment. One hundred twenty-eight fish in 8 national parks in Alaska and the western U.S. were analyzed for contaminant concentrations, assessed by region, and compared to human and wildlife health thresholds. SOC concentrations from an additional 133 fish from a previous study were also included, for a total of 31 water bodies sampled. PCBs, endosulfan sulfate, and p,p′-DDE were among the most frequently detected contaminants. Concentrations of historic-use pesticides dieldrin, p,p′-DDE, and/or chlordanes in fish exceeded USEPA guidelines for human subsistence fish consumers and wildlife (kingfisher) health thresholds at 13 of 14 parks. Average concentrations in fish ranged from 0.6-280 ng/g lipid (0.02-7.3 μg/g ww). Contaminant loading was highest in fish from Alaskan and Sierra Nevada parks. Historic compounds were highest in Alaskan parks, while current-use pesticides were higher in the Rockies and Sierra Nevada. This study provides a rigorous analysis of CECs in fish from national parks and identifies regions at potential risk.Keywords: Semivolatile organic compounds, National parks, Fish, Consumption thresholdsKeywords: Semivolatile organic compounds, National parks, Fish, Consumption threshold

Dual Delivery of EPO and BMP2 from a Novel Modular Poly-ɛ-Caprolactone Construct to Increase the Bone Formation in Prefabricated Bone Flaps

Poly-?-caprolactone (PCL) is a biocompatible polymer that has mechanical properties suitable for bone tissue engineering; however, it must be integrated with biologics to stimulate bone formation. Bone morphogenetic protein-2 (BMP2) delivered from PCL produces bone when implanted subcutaneously, and erythropoietin (EPO) works synergistically with BMP2. In this study, EPO and BMP2 are adsorbed separately on two 3D-printed PCL scaffold modules that are assembled for codelivery on a single scaffold structure. This assembled modular PCL scaffold with dual BMP2 and EPO delivery was shown to increase bone growth in an ectopic location when compared with BMP2 delivery along a replicate scaffold structure. EPO (200?IU/mL) and BMP2 (65??g/mL) were adsorbed onto the outer and inner portions of a modular scaffold, respectively. Protein binding and release studies were first quantified. Subsequently, EPO+BMP2 and BMP2 scaffolds were implanted subcutaneously in mice for 4 and 8 weeks, and the regenerated bone was analyzed with microcomputed tomography and histology; 8.6±1.4??g BMP2 (22%) and 140±29?IU EPO (69.8%) bound to the scaffold and <1% BMP2 and 83% EPO was released in 7 days. Increased endothelial cell proliferation on EPO-adsorbed PCL discs indicated protein bioactivity. At 4 and 8 weeks, dual BMP2 and EPO delivery regenerated more bone (5.1±1.1 and 5.5±1.6?mm3) than BMP2 alone (3.8±1.1 and 4.3±1.7?mm3). BMP2 and EPO scaffolds had more ingrowth (1.4%±0.6%) in the outer module when compared with BMP2 (0.8%±0.3%) at 4 weeks. Dual delivery produced more dense cellular marrow, while BMP2 had more fatty marrow. Dual EPO and BMP2 delivery is a potential method to regenerate bone faster for prefabricated flaps.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140252/1/ten.tec.2014.0643.pd