Development of fibroblast/endothelial cell-seeded collagen scaffolds for in vitro prevascularization.

The development of vascularized scaffolds remains one of the major challenges in tissue engineering, and co-culturing with endothelial cells is known as one of the possible approaches for this purpose. In this approach, optimization of cell culture conditions, scaffolds, and fabrication techniques is needed to develop tissue equivalents that will enable in vitro formation of a capillary network. Prevascularized equivalents will be more physiologically comparable to the native tissues and potentially prevent insufficient vascularization after implantation.

A comparison of the inflammatory host response to particulate debris adjacent to unlocked and locked screws of a growth guidance system for early onset scoliosis.

Purpose: The SHILLA™ Growth Guidance system is a stainless-steel rod and screw system used for Early Onset Scoliosis which incorporates a unique flanged set screw designed to capture the rod, while allowing it to slide as the patient grows. Concomitant with this design is the potential for generation of wear debris and for an inflammatory host response. We hypothesized that the magnitude of the host response adjacent to the unlocked screws and rods would be greater than the host response to the locked rod/screws.

Biological resurfacing in a canine model of hip osteoarthritis.

Articular cartilage has unique load-bearing properties but has minimal capacity for intrinsic repair. Here, we used three-dimensional weaving, additive manufacturing, and autologous mesenchymal stem cells to create a tissue-engineered, bicomponent implant to restore hip function in a canine hip osteoarthritis model. This resorbable implant was specifically designed to function mechanically from the time of repair and to biologically integrate with native tissues for long-term restoration.

An evaluation of the host response to an interspinous process device based on a series of spine explants: Device for Intervertebral Assisted Motion (DIAM).

Background: The objective of this study was to evaluate the host response to an interspinous process device [Device for Intervertebral Assisted Motion (DIAM)] based on a series of nine spine explants with a mean post-operative explant time of 35 months.

Methods: Explanted periprosthetic tissues were processed for histology and stained with H&E, Wright-Giemsa stain, and Oil Red O. Brightfield and polarized light microscopy were used to evaluate the host response to the device and the resultant particulate debris.

Early term effects of rhBMP-2 on pedicle screw fixation in a sheep model: histomorphometric and biomechanical analyses.

Background: The effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) on pedicle screw pullout force and its potential to improve spinal fixation have not previously been investigated. rhBMP-2 on an absorbable collagen sponge (ACS) carrier was delivered in and around cannulated and fenestrated pedicle screws in a sheep lumbar spine instability model. Two control groups (empty screw and ACS with buffer) were also evaluated.

Opioids delay healing of spinal fusion: a rabbit posterolateral lumbar fusion model.

Background Context: Opioid use is prevalent in the management of pre- and postoperative pain in patients undergoing spinal fusion. There is evidence that opioids downregulate osteoblasts in vitro, and a previous study found that morphine delays the maturation and remodeling of callus in a rat femur fracture model. However, the effect of opioids on healing of spinal fusion has not been investigated before.

The temporal expression of adipokines during spinal fusion.

Background Context: Adipokines are secreted by white adipose tissue and have been associated with fracture healing. Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

Purpose: Our goal was to report the temporal expression of adipokines during spinal fusion in an established rabbit model.

Is lumbar facet fusion biomechanically equivalent to lumbar posterolateral onlay fusion?

OBJECTIVE This study was designed with the following research objectives: 1) to determine the efficacy of facet fusion with recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) in an ovine lumbar facet fusion model; 2) to radiographically and histologically compare the efficacy of lumbar facet fusion with rhBMP-2/ACS to facet fusion with an iliac crest bone graft (ICBG); and 3) to biomechanically compare lumbar facet fusion with rhBMP-2/ACS to lumbar posterolateral fusion (PLF) with ICBG. METHODS The efficacies of the 3 treatments to induce fusion were evaluated in an instrumented ovine lumbar fusion model. Eight sheep had 10 cm/side ICBG placed as an onlay graft for PLF at L2-3.

Transient Local Bone Remodeling Effects of rhBMP-2 in an Ovine Interbody Spine Fusion Model.

Background: Recombinant human bone morphogenetic protein-2 (rhBMP-2) is a powerful osteoinductive morphogen capable of stimulating the migration of mesenchymal stem cells (MSCs) to the site of implantation and inducing the proliferation and differentiation of these MSCs into osteoblasts. Vertebral end-plate and vertebral body resorption has been reported after interbody fusion with high doses of rhBMP-2. In this study, we investigated the effects of 2 rhBMP-2 doses on peri-implant bone resorption and bone remodeling at 7 time points in an end-plate-sparing ovine interbody fusion model.

Radiographic, biomechanical, and histological evaluation of rhBMP-2 in a 3-level intertransverse process spine fusion: an ovine study.

OBJECTIVE The objective of this study was to evaluate bone grafts consisting of rhBMP-2 on an absorbable collagen sponge with a ceramic composite bulking agent, rhBMP-2, directly on a ceramic-collagen sponge carrier or iliac crest bone graft (ICBG) in combination with local bone graft to effect fusion in a multisegmental instrumented ovine lumbar intertransverse process fusion model. METHODS Thirty-six sheep had a single treatment at 3 spinal levels in both the right and left intertransverse process spaces. Group 1 sheep were treated with 7.

Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep.

Study Design: Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft.

Objective: The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively.

Category cued recall evokes a generate-recognize retrieval process.

The experiments reported here were designed to replicate and extend McCabe, Roediger, and Karpicke's (2011) finding that retrieval in category cued recall involves both controlled and automatic processes. The extension entailed identifying whether distinctive encoding affected 1 or both of these 2 processes. The first experiment successfully replicated McCabe et al.

Which design and biomaterial factors affect clinical wear performance of total disc replacements? A systematic review.

Background: Total disc replacement was clinically introduced to reduce pain and preserve segmental motion of the lumbar and cervical spine. Previous case studies have reported on the wear and adverse local tissue reactions around artificial prostheses, but it is unclear how design and biomaterials affect clinical outcomes.

Questions/purposes: Which design and material factors are associated with differences in clinical wear performance (implant wear and periprosthetic tissue response) of (1) lumbar and (2) cervical total disc replacements?

Methods: We performed a systematic review on the topics of implant wear and periprosthetic tissue response using an advanced search in MEDLINE and Scopus electronic databases.

Bone properties by nanoindentation in mild and severe osteogenesis imperfecta.

Background: Osteogenesis imperfecta is a heterogeneous genetic disorder characterized by bone fragility. Previous research suggests that impaired collagen network and abnormal mineralization affect bone tissue properties, however, little data is yet available to describe bone material properties in individuals with this disorder. Bone material properties have not been characterized in individuals with the most common form of osteogenesis imperfecta, type I.

Early-term and mid-term histologic events during single-level posterolateral intertransverse process fusion with rhBMP-2/collagen carrier and a ceramic bulking agent in a nonhuman primate model: implications for bone graft preparation.

Study Design: We used a nonhuman primate lumbar intertransverse process arthrodesis model to evaluate biological cascade of bone formation using different carrier preparation methods with a single dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) at early time points.

Objective: To examine early-term/mid-term descriptive histologic and computerized tomographic events in single-level uninstrumented posterolateral nonhuman primate spinal fusions using rhBMP-2/absorbable collagen sponge (ACS) combined with ceramic bulking agents in 3 different configurations.

Summary Of Background Data: rhBMP-2 on an ACS carrier alone leads to consistent posterolateral lumbar spine fusions in lower-order animals; however, these results have been difficult to replicate in nonhuman primates.

Altered hemodynamics, endothelial function, and protein expression occur with aortic coarctation and persist after repair.

Coarctation of the aorta (CoA) is associated with substantial morbidity despite treatment. Mechanically induced structural and functional vascular changes are implicated; however, their relationship with smooth muscle (SM) phenotypic expression is not fully understood. Using a clinically representative rabbit model of CoA and correction, we quantified mechanical alterations from a 20-mmHg blood pressure (BP) gradient in the thoracic aorta and related the expression of key SM contractile and focal adhesion proteins with remodeling, relaxation, and stiffness.

Chronically inadequate sleep results in abnormal bone formation and abnormal bone marrow in rats.

Insufficient sleep over long durations of the lifespan is believed to adversely affect proper development and healthful aging, although how this might become manifested is unknown. In the present study, rats were repeatedly sleep-restricted during 72 days to permit maladaptations to evolve, thereby permitting study. Densitometric and histomorphometric analyses were performed on harvested bone.

The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements.

Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods.

A coupled experimental and computational approach to quantify deleterious hemodynamics, vascular alterations, and mechanisms of long-term morbidity in response to aortic coarctation.

Introduction: Coarctation of the aorta (CoA) is associated with morbidity despite treatment. Although mechanisms remain elusive, abnormal hemodynamics and vascular biomechanics are implicated. We present a novel approach that facilitates quantification of coarctation-induced mechanical alterations and their impact on vascular structure and function, without genetic or confounding factors.

What you know can hurt you: effects of age and prior knowledge on the accuracy of judgments of learning.

How do aging and prior knowledge affect memory and metamemory? We explored this question in the context of a dual-process approach to Judgments of Learning (JOLs), which require people to predict their ability to remember information at a later time. Young and older adults (n = 36, mean ages = 20.2 & 73.

Aging and recollection in the accuracy of judgments of learning.

Dual-process theories propose that episodic memory performance reflects both recollection of prior details as well as more automatic influences of the past. The authors explored the idea that recollection mediates the accuracy of judgments of learning (JOLs) and may also help explain age differences in JOL accuracy. Young and older adults made immediate JOLs at study and then completed recognition or recall tests that included a recollect/familiar judgment.

Bioresorbable film for the prevention of adhesion to the anterior spine after anterolateral discectomy.

Background Context: The development of scar tissue and adhesions postoperatively is a natural consequence of healing but can be associated with medical complications and render reoperation difficult. Many biocompatible products have been evaluated as barriers or deterrents to adhesions.

Purpose: To evaluate the efficacy of a bioresorbable polylactide film as a barrier to adhesion formation after anterolateral discectomy.

Short-term osteoclastic activity induced by locally high concentrations of recombinant human bone morphogenetic protein-2 in a cancellous bone environment.

Study Design: An experimental study investigating osteoclastic activity induced by rhBMP-2 in sheep.

Objective: To examine the effects of increasing local rhBMP-2 concentration on osteoclastic response and peri-implant bone resorption.

Summary Of Background Data: Level I clinical studies have established the safe and effective volume and concentration of rhBMP-2 delivered on an absorbable collagen sponge.

Multiple levels of control in the Stroop task.

Multiple levels of control may be used in service of reducing Stroop interference. One is list-wide, whereby interference is reduced strategically in lists that include disproportionately more incongruent trials. A second, item-specific control is observed when proportion congruence is manipulated at the level of items.