An In Vivo Assessment of Different Mesenchymal Stromal Cell Tissue Types and Their Differentiation State on a Shape Memory Polymer Scaffold for Bone Regeneration.

A combined biomaterial and cell-based solution to heal critical size bone defects in the craniomaxillofacial area is a promising alternative therapeutic option to improve upon autografting, the current gold standard. A shape memory polymer (SMP) scaffold, composed of biodegradable poly(ε-caprolactone) and coated with bioactive polydopamine, was evaluated with mesenchymal stromal cells (MSCs) derived from adipose (ADSC), bone marrow (BMSC), or umbilical cord (UCSC) tissue in their undifferentiated state or pre-differentiated toward osteoblasts for bone healing in a rat calvarial defect model. Pre-differentiating ADSCs and UCSCs resulted in higher new bone volume fraction (15.

Shape Memory Polymer Scaffolds-Utility for In Vitro Osteogenesis of Canine Multipotent Stromal Cells.

A biodegradable, shape memory polymer (SMP) scaffold based on poly(ε-caprolactone) (PCL) represents an attractive alternative therapy for the repair of critically sized bone defects given its ability to press-fit within irregular defects. Clinical translation of SMP scaffolds requires successful movement beyond proof-of-concept rodent studies through a relevant large-animal model and into the clinical setting. In addition to representing a clinical veterinary population, the canine species is a strong translational model for humans due to similarities in orthopedic disorders, biomechanics, and bone healing.

Computational Model-Assisted Development of a Nonenzymatic Fluorescent Glucose-Sensing Assay.

Deep-red fluorescence was implemented in this fully injectable, nonenzymatic glucose biosensor design to allow for better light penetration through the skin, particularly for darker skin tones. In this work, a novel method was developed to synthesize Cy5.5 labeled mannose conjugates (Cy5.

Network interactions simultaneously enhance stiffness and lubricity of triple-network hydrogels.

Synthetic hydrogels displaying cartilage-mimetic bulk and surface properties may serve as cartilage substitutes. Multi-network, electrostatic hydrogels that leverage intra- and inter-network repulsive and attractive forces represent a promising approach. Herein, triple network (TN) hydrogels were prepared to obtain a combination of desired characteristics (, hydration, stiffness, shear stress, and friction properties).

Biocompatibility and Bone Regeneration by Shape Memory Polymer Scaffolds.

Biodegradable, shape memory polymer (SMP) scaffolds based on poly(ε-caprolactone) (PCL) offer unique advantages as a regenerative treatment strategy for critical-sized bone defects. In particular, a conformal fit may be achieved following exposure to warm saline, thereby improving osseointegration and regeneration. Advancing the clinical translation of these SMP scaffolds requires establishment of efficacy not only in non-loading models, but also load-bearing or load-sharing models.

Shape Memory Polymer Bioglass Composite Scaffolds Designed to Heal Complex Bone Defects.

An off-the-shelf scaffold with requisite properties could enable the viable treatment of irregular craniomaxillofacial bone defects. Notably, the scaffold should be conformally fitting, innately bioactive, and bioresorbable. In prior work, we developed a series of shape memory polymer (SMP) scaffolds based on cross-linked poly(ε-caprolactone) (PCL).

Polycaprolactone-based shape memory foams as self-fitting vaginal stents.

There is an urgent critical need for a patient-forward vaginal stent that can prevent debilitating vaginal stenosis that occurs after pelvic radiation treatments and vaginal reconstruction. To this end, we developed a self-fitting vaginal stent based on a shape-memory polymer (SMP) foam that can assume a secondary, compressed shape for ease of deployment. Upon insertion, the change in temperature and hydration initiates foam expansion to shape fit to the individual patient and restore the lumen of the stent to allow egress of vaginal secretions.

-PCL shape memory polymer (SMP) scaffolds with tunable transition temperatures for enhanced utility.

Thermoresponsive shape memory polymers (SMPs) prepared from UV-curable poly(ε-caprolactone) (PCL) macromers have the potential to create self-fitting bone scaffolds, self-expanding vaginal stents, and other shape-shifting devices. To ensure tissue safety during deployment, the shape actuation temperature (, the melt transition temperature or of PCL) must be reduced from ∼55 °C that is observed for scaffolds prepared from -PCL-DA ( ∼ 10 kg mol). Moreover, increasing the rate of biodegradation would be advantageous, facilitating bone tissue healing and potentially eliminating the need for stent retrieval.

High-Throughput Screening of Thiol-ene Click Chemistries for Bone Adhesive Polymers.

Metal surgical pins and screws are employed in millions of orthopedic surgical procedures every year worldwide, but their usability is limited in the case of complex, comminuted fractures or in surgeries on smaller bones. Therefore, replacing such implants with a bone adhesive material has long been considered an attractive option. However, synthesizing a biocompatible bone adhesive with a high bond strength that is simple to apply presents many challenges.

Amphiphilic silicones for the facile dispersion of carbon nanotubes and formation of soft skin electrodes.

Flexible, dry skin electrodes represent a potentially superior alternative to standard Ag/AgCl metal electrodes for wearable devices used in long-term monitoring. Herein, such electrodes were formed using a facile method for dispersing carbon nanotubes (CNTs) in a silicone matrix using custom amphiphilic dispersive additives (DSPAs). Using only brief mixing and without the use of solvents or surface modification of CNTs, twelve poly(ethylene oxide)-silanes (PEO-SAs) of varying crosslinkability, architecture, siloxane tether length, and molar ratio of siloxane:PEO were combined with an addition cure silicone and CNTs.

Adhesive Hydrogel Building Blocks to Reconstruct Complex Cartilage Tissues.

Cartilage has an intrinsically low healing capacity, thereby requiring surgical intervention. However, limitations of biological grafting and existing synthetic replacements have prompted the need to produce cartilage-mimetic substitutes. Cartilage tissues perform critical functions that include load bearing and weight distribution, as well as articulation.

Biomedical Silicones: Leveraging Additive Strategies to Propel Modern Utility.

Silicones have a long history of use in biomedical devices, with unique properties stemming from the siloxane (Si-O-Si) backbone that feature a high degree of flexibility and chemical stability. However, surface, rheological, mechanical, and electrical properties of silicones can limit their utility. Successful modification of silicones to address these limitations could lead to superior and new biomedical devices.

Emerging polymeric material strategies for cartilage repair.

Cartilage is found throughout the body, serving an array of essential functions. Owing to the limited healing capacity of cartilage, damage or degeneration is often permanent and so requires clinical intervention. Established surgical techniques generally rely on biological grafting.

Ultra-High Modulus Hydrogels Mimicking Cartilage of the Human Body.

The human body is comprised of numerous types of cartilage with a range of high moduli, despite their high hydration. Owing to the limitations of cartilage tissue healing and biological grafting procedures, synthetic replacements have emerged but are limited by poorly matched moduli. While conventional hydrogels can achieve similar hydration to cartilage tissues, their moduli are substantially inferior.

Silicone-containing thermoresponsive membranes to form an optical glucose biosensor.

Glucose biosensors that could be subcutaneously injected and interrogated without a physically connected electrode and transmitter affixed to skin would represent a major advancement in reducing the user burden of continuous glucose monitors (CGMs). Towards this goal, an optical glucose biosensor was formed by strategically tailoring a thermoresponsive double network (DN) membrane to house a phosphorescence lifetime-based glucose sensing assay. This membrane was selected based on its potential to exhibit reduced biofouling 'self-cleaning' due to cyclical deswelling/reswelling .

Comparative evaluation of mesenchymal stromal cell growth and osteogenic differentiation on a shape memory polymer scaffold.

Trauma-induced, critical-size bone defects pose a clinical challenge to heal. Albeit autografts are the standard-of-care, they are limited by their inability to be shaped to various defect geometries and often incur donor site complications. Herein, the combination of a "self-fitting" shape memory polymer (SMP) scaffold and seeded mesenchymal stromal cells (MSCs) was investigated as an alternative.

Amphiphilic silicones to mitigate lens epithelial cell growth on intraocular lenses.

Silicone intraocular lenses (IOLs) that resist lens epithelial cell (LEC) growth would greatly improve patient outcomes. Herein, amphiphilic surface modifying additives (SMAs) were incorporated into an IOL-type diphenyl silicone to reduce LEC growth without compromising opto-mechanical properties. The SMAs were poly(ethylene oxide)-silane amphiphiles (PEO-SAs) [H-Si-ODMS--PEO-OCH], comprised of a PEO segment and siloxane tether of varying lengths ( = 0, 13, and 30).

A Glucose Biosensor Based on Phosphorescence Lifetime Sensing and a Thermoresponsive Membrane.

The adoption of existing continuous glucose monitors (CGMs) is limited by user burden. Herein, a design for a glucose biosensor with the potential for subcutaneous implantation, without the need for a transcutaneous probe or affixed transmitter, is presented. The design is based on the combination of an enzyme-driven phosphorescence lifetime-based glucose-sensing assay and a thermoresponsive membrane anticipated to reduce biofouling.

PoreScript: Semi-automated pore size algorithm for scaffold characterization.

The scaffold pore size influences many critical physical aspects of tissue engineering, including tissue infiltration, biodegradation rate, and mechanical properties. Manual measurements of pore sizes from scanning electron micrographs using ImageJ/FIJI are commonly used to characterize scaffolds, but these methods are both time-consuming and subject to user bias. Current semi-automated analysis tools are limited by a lack of accessibility or limited sample size in their verification process.

Suitability of EtO Sterilization for Polydopamine-coated, Self-fitting Bone Scaffolds.

Irregularly shaped craniomaxillofacial (CMF) defects may be advantageously treated by "self-fitting" shape memory polymer (SMP) scaffolds, namely those prepared from poly(ε-caprolactone)diacrylate (PCL-DA) networks and PCL-DA/poly(L-lactic acid) (PLLA) (75:25 wt%) semi-interpenetrating polymer networks (semi-IPNs). In addition to achieving good scaffold-tissue contact, a polydopamine (PD) coating can be leveraged to enhance bioactivity for improved osseointegration. Sterilization with ethylene oxide (EtO) represents a logical choice due to its low operating temperature and humidity.

Methodology for performing biomechanical push-out tests for evaluating the osseointegration of calvarial defect repair in small animal models.

Push-out tests are frequently used to evaluate the bone-implant interfacial strength of orthopedic implants, particularly dental and craniomaxillofacial applications. There currently is no standard method for performing push-out tests on calvarial models, leading to a variety of inconsistent approaches. In this study, fixtures and methods were developed to perform push-out tests in accordance with the following design objectives: (i) the system rigidly fixes the explanted calvarial sample, (ii) it minimizes lateral bending, (iii) it positions the defect accurately, and (iv) it permits verification of the coaxial alignment of the defect with the push-out rod.

Evaluation of a self-fitting, shape memory polymer scaffold in a rabbit calvarial defect model.

Self-fitting scaffolds prepared from biodegradable poly(ε-caprolactone)-diacrylate (PCL-DA) have been developed for the treatment of craniomaxillofacial (CMF) bone defects. As a thermoresponsive shape memory polymer (SMP), with the mere exposure to warm saline, these porous scaffolds achieve a conformal fit in defects. This behavior was expected to be advantageous to osseointegration and thus bone healing.

Intrinsic osteoinductivity of PCL-DA/PLLA semi-IPN shape memory polymer scaffolds.

Engineering osteoinductive, self-fitting scaffolds offers a potential treatment modality to repair irregularly shaped craniomaxillofacial bone defects. Recently, we innovated on osteoinductive poly(ε-caprolactone)-diacrylate (PCL-DA) shape memory polymers (SMPs) to incorporate poly-L-lactic acid (PLLA) into the PCL-DA network, forming a semi-interpenetrating network (semi-IPN). Scaffolds formed from these PCL-DA/PLLA semi-IPNs display stiffnesses within the range of trabecular bone and accelerated degradation relative to scaffolds formed from slowly degrading PCL-DA SMPs.

Shape memory polymer (SMP) scaffolds with improved self-fitting properties.

"Self-fitting" shape memory polymer (SMP) scaffolds prepared as semi-interpenetrating networks (semi-IPNs) with crosslinked linear-poly(ε-caprolactone)-diacrylate (PCL-DA, M∼10 kg mol) and linear-poly(l-lactic acid) (PLLA, M∼15 kg mol) [75/25 wt%] exhibited robust mechanical properties and accelerated degradation rates versus a PCL-DA scaffold control. However, their potential to treat irregular craniomaxillofacial (CMF) bone defects is limited by their relatively high fitting temperature (T∼55 °C; related to the T of PCL) required for shape recovery (i.e.