A supramolecular polymer-collagen microparticle slurry for bone regeneration with minimal growth factor.

Recombinant bone morphogenetic protein-2 (BMP-2) is a potent osteoinductive growth factor that can promote bone regeneration for challenging skeletal repair and even for ectopic bone formation in spinal fusion procedures. However, serious clinical side effects related to supraphysiological dosing highlight the need for advances in novel biomaterials that can significantly reduce the amount of this biologic. Novel biomaterials could not only reduce clinical side effects but also expand the indications for use of BMP-2, while at the same time lowering the cost of such procedures. To achieve this objective, we have developed a slurry containing a known supramolecular polymer that potentiates BMP-2 signaling and porous collagen microparticles. This slurry exhibits a paste-like consistency that stiffens into an elastic gel upon implantation making it ideal for minimally invasive procedures. We carried out in vivo evaluation of the novel biomaterial in the rabbit posterolateral spine fusion model, and discovered efficacy at unprecedented ultra-low BMP-2 doses (5 µg/implant). This dose reduces the growth factor requirement by more than 100-fold relative to current clinical products. This observation is significant given that spinal fusion involves ectopic bone formation and the rabbit model is known to be predictive of human efficacy. We expect the novel biomaterial can expand BMP-2 indications for difficult cases requiring large volumes of bone formation or involving patients with underlying conditions that compromise bone regeneration.

Sex-based Difference in Response to Recombinant Human Bone Morphogenetic Protein-2 in a Rat Posterolateral Fusion Model.

STUDY DESIGN: This was a preclinical study. OBJECTIVE: Evaluate sex-dependent differences in the bone healing response to recombinant human bone morphogenetic protein-2 (rhBMP-2) in a rat posterolateral spinal fusion model. SUMMARY OF BACKGROUND DATA: Minimal and conflicting data exist concerning potential sex-dependent differences in rhBMP-2-mediated bone regeneration in the context of spinal fusion. MATERIALS AND METHODS: Forty-eight female and male Sprague-Dawley rats (N=24/group), underwent L4-L5 posterolateral fusion with bilateral placement of an absorbable collagen sponge, each loaded with 5 µg of bone morphogenetic protein-2 (10 µg/animal). At eight weeks postoperative, 10 specimens of each sex were tested in flexion-extension with quantification of range of motion and stiffness. The remaining specimens were evaluated for new bone growth and successful fusion via radiography, blinded manual palpation and microcomputed tomography (microCT). Laboratory microCT quantified bone microarchitecture, and synchrotron microCT examined bone microstructure at the 1 µm level. RESULTS: Manual palpation scores differed significantly between sexes, with mean fusion scores of 2.4±0.4 in females versus 3.1±0.6 in males ( P <0.001). Biomechanical stiffness did not differ between sexes, but range of motion was significantly greater and more variable for females versus males (3.7±5.6° vs. 0.27±0.15°, P <0.005, respectively). Laboratory microCT showed significantly smaller volumes of fusion masses in females versus males (262±87 vs. 732±238 mm 3 , respectively, P <0.001) but significantly higher bone volume fraction (0.27±0.08 vs. 0.12±0.05, respectively, P <0.001). Mean trabecular thickness was not different, but trabecular number was significantly greater in females (3.1±0.5 vs. 1.5±0.4 mm -1 , respectively, P <0.001). Synchrotron microCT showed fine bone structures developing in both sexes at the eight-week time point. CONCLUSIONS: This study demonstrates sex-dependent differences in bone regeneration induced by rhBMP-2. Further investigation is needed to uncover the extent of and mechanisms underlying these sex differences, particularly at different doses of rhBMP-2.

Preclinical Safety of a 3D-Printed Hydroxyapatite-Demineralized Bone Matrix Scaffold for Spinal Fusion.

STUDY DESIGN: Prospective, randomized, controlled preclinical study. OBJECTIVE: The objective of this study was to compare the host inflammatory response of our previously described hyperelastic, 3D-printed (3DP) hydroxyapatite (HA)-demineralized bone matrix (DBM) composite scaffold to the response elicited with the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a preclinical rat posterolateral lumbar fusion model. SUMMARY OF BACKGROUND DATA: Our group previously found that this 3D-printed HA-DBM composite material shows promise as a bone graft substitute in a preclinical rodent model, but its safety profile had yet to be assessed. METHODS: Sixty female Sprague-Dawley rats underwent bilateral posterolateral intertransverse lumbar spinal fusion using with the following implants: 1) type I absorbable collagen sponge (ACS) alone; 2) 10 µg rhBMP-2/ACS; or 3) the 3DP HA-DBM composite scaffold (n = 20). The host inflammatory response was assessed using magnetic resonance imaging, while the local and circulating cytokine expression levels were evaluated by enzyme-linked immunosorbent assays at subsequent postoperative time points (N = 5/time point). RESULTS: At both 2 and 5 days postoperatively, treatment with the HA-DBM scaffold produced significantly less soft tissue edema at the fusion bed site relative to rhBMP-2-treated animals as quantified on magnetic resonance imaging. At every postoperative time point evaluated, the level of soft tissue edema in HA-DBM-treated animals was comparable to that of the ACS control group. At 2 days postoperatively, serum concentrations of tumor necrosis factor-α and macrophage chemoattractant protein-1 were significantly elevated in the rhBMP-2 treatment group relative to ACS controls, whereas these cytokines were not elevated in the HA-DBM-treated animals. CONCLUSION: The 3D-printed HA-DBM composite induces a significantly reduced host inflammatory response in a preclinical spinal fusion model relative to rhBMP-2.Level of Evidence: N/A.

Osteoinductivity and biomechanical assessment of a 3D printed demineralized bone matrix-ceramic composite in a rat spine fusion model.

We recently developed a recombinant growth factor-free bone regenerative scaffold composed of stoichiometric hydroxyapatite (HA) ceramic particles and human demineralized bone matrix (DBM) particles (HA-DBM). Here, we performed the first pre-clinical comparative evaluation of HA-DBM relative to the industry standard and established positive control, recombinant human bone morphogenetic protein-2 (rhBMP-2), using a rat posterolateral spinal fusion model (PLF). Female Sprague-Dawley rats underwent bilateral L4-L5 PLF with implantation of the HA-DBM scaffold or rhBMP-2. Fusion was evaluated using radiography and blinded manual palpation, while biomechanical testing quantified the segmental flexion-extension range-of-motion (ROM) and stiffness of the fused segments at 8-weeks postoperatively. For mechanistic studies, pro-osteogenic gene and protein expression at 2-days and 1-, 2-, and 8-weeks postoperatively was assessed with another cohort. Unilateral fusion rates did not differ between the HA-DBM (93%) and rhBMP-2 (100%) groups; however, fusion scores were higher with rhBMP-2 (p = 0.008). Both treatments resulted in significantly reduced segmental ROM (p < 0.001) and greater stiffness (p = 0.009) when compared with non-operated controls; however, the degree of stabilization was significantly higher with rhBMP-2 treatment relative to the HA-DBM scaffold. In the mechanistic studies, PLGA and HA scaffolds were used as negative controls. Both rhBMP-2 and HA-DBM treatments resulted in significant elevations of several osteogenesis-associated genes, including Runx2, Osx, and Alp. The rhBMP-2 treatment led to significantly greater early, mid, and late osteogenic markers, which may be the mechanism in which early clinical complications are seen. The HA-DBM scaffold also induced osteogenic gene expression, but primarily at the 2-week postoperative timepoint. Overall, our findings show promise for this 3D-printed composite as a recombinant growth factor-free bone graft substitute for spinal fusion. STATEMENT OF SIGNIFICANCE: Despite current developments in bone graft technology, there remains a significant void in adequate materials for bone regeneration in clinical applications. Two of the most efficacious bone graft options are the gold-standard iliac crest bone graft and recombinant human-derived bone morphogenetic protein-2 (rhBMP-2), available commercially as Infuse™. Although efficacious, autologous graft is associated with donor-site morbidity, and Infuse™ has known side effects related to its substantial host inflammatory response, possibly associated with a immediate, robust osteoinductive response. Hence, there is a need for a bone graft substitute that provides adequate osteogenesis without associated adverse events. This study represents a significant step in the design of off-the-shelf growth factor-free devices for spine fusion.

Characterizing the host response to rhPDGF-BB in a rat spinal arthrodesis model.

BACKGROUND: Due to the constraints surrounding autograft bone, surgeons have turned to osteoinductive agents to augment spinal fusion. Reports of complications and questionable efficacy slowed the adoption of these alternatives. Recombinant human platelet-derived growth factor B homodimer (rhPDGF-BB) has been Food and Drug Administration (FDA)-approved (Augment) to promote fusion in other areas of orthopedics, but its characterization in spine fusion has not yet been tested. The purpose of this study is to characterize the host response to PDGF-BB in vivo. METHODS: Eighty female Fischer rats underwent L4-5 posterolateral fusion using one of four implant types: (a) iliac crest syngeneic allograft harvested from syngeneic donors, (b) ß-TCP/bovine collagen matrix (ß-TCP/Col) with sodium acetate buffer, (c) ß-TCP/Col with 0.3 mg/mL "low dose," or (d) ß-TCP/Col with 3.0 mg/mL "high dose" of rhPDGF-BB. Animals underwent magnetic resonance imaging (MRI) and serum cytokine quantification at 4, 7, 10, and 21 days, postoperatively. Tissues were processed for immunofluorescence staining for Ki67 and von Willebrand factor (vWF) to assess neovascularization. RESULTS: MRI demonstrated no differences in fluid accumulation among the four treatment groups at any of the time points. Serum cytokine analysis showed no clinically significant differences between treatment groups in 20 of the 27 cytokines. Inflammatory cytokines IFN-γ, IL-1ß, IL-18, MCP-1, MIP-1α, TNF-α were not induced by rhPDGF-BB. Histology showed no differences in cell infiltration, and Ki67 and vWF immunofluorescence staining was similar among groups. CONCLUSIONS: rhPDGF-BB delivered with a ß-TCP/Col matrix exerts no exaggerated systemic or local host inflammatory response when compared to iliac crest syngeneic allograft bone or the control carrier. rhPDGF-BB mixed with a ß-TCP/Col matrix could be a viable and safe biologic alternative to syngeneic allograft in spine fusion. Further studies need to be performed to evaluate efficacy in this setting.

The effect of local steroid application on bony fusion in a rat posterolateral spinal arthrodesis model.

INTRODUCTION: Local steroid administration during anterior cervical spine surgery has been shown to improve postoperative dysphagia. However, concerns over potential complications remain. This study aims to evaluate the effect of local steroid administration on bone regeneration and spine fusion in a preclinical model, as well as the impact on osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) in a 3D culture system. MATERIALS AND METHODS: Forty-five rats underwent bilateral L4-L5 posterolateral lumbar fusion (PLF) utilizing local delivery of low-dose recombinant human bone morphogenetic protein-2 (rhBMP-2; 0.5 µg/implant). Rats were divided into three groups: no steroid (control), low dose (0.5 mg/kg), and high dose (2.5 mg/kg) of triamcinolone. Bone growth and fusion were assessed using radiography, blinded manual palpation, and micro-CT analysis and were visualized by histology. The impact of triamcinolone exposure on osteogenic differentiation of hBM-MSCs was evaluated by gene expression analysis, alkaline phosphatase activity assay, and alizarin red staining. RESULTS: No significant differences in fusion scores or rates were seen in the low- or high-dose steroid treatment groups relative to untreated controls. Quantification of new bone formation via micro-CT imaging revealed no significant between-group differences in the volume of newly regenerated bone. Triamcinolone also had no negative impact on pro-osteogenic gene transcript levels, and ALP activity was enhanced in the presence of triamcinolone. Mineral deposition appeared comparable in cultures grown with and without triamcinolone. CONCLUSIONS: Local steroid application does not seem to inhibit rhBMP-2-mediated spine fusion in rats, though our study may not be adequately powered to detect differences in fusion as measured by manual palpation or bone volume as measured by micro-CT. These findings suggest that local triamcinolone may not increase pseudarthrosis in spine fusion procedures. Further large animal and clinical studies to verify its safety and efficacy are warranted.

Development of MnO2 hollow nanoparticles for potential drug delivery applications.

This study reports the development of hollow nanoparticles, formed from manganese dioxide (δ-MnO2) sheets, that are coated with polydopamine for potential immobilization of chemical agents. The biodegradability and colloidal stability of the uncoated hollow MnO2 nanoparticles were investigated in comparison to commercially synthesized solid MnO2 nanoparticles and graphene oxide sheets. The MnO2 hollow nanoparticles degraded at a faster rate and seem to have a higher surface area and better colloidal dispersion than solid MnO2 nanoparticles. Xanthan gum (as a dispersant) was proven to improve colloidal dispersion of these hollow nanoparticles and were used for further cell studies. In this study, cancer and healthy cells were treated with coated hollow nanoparticles, and the studies indicate that this novel nanoparticle can internalize cells. Particle aggregation has shown to inhibit cell growth. Further studies with this novel hollow nanoparticle may lead to a groundbreaking solution to new drug delivery systems for cancers or other applications.

Orthobiologics in minimally invasive lumbar fusion.

Minimally invasive (MI) spine surgery continues to gain popularity with patients and surgeons for its potential to decrease operative time and avoid complications commonly associated with open surgery. In the face of a changing surgical landscape, selecting the appropriate implant material to be used in MI lumbar fusion procedures will remain critically important. Various orthobiologic materials are available for use, including autologous and allogeneic bone graft, bone marrow aspirate (BMA), demineralized bone matrix (DBM), ceramics, and growth factors. The purpose of this review is to summarize the use and efficacy of currently available products, as well as highlight the development of novel therapeutic options.

Frontal lobe functioning during a simple response conflict task in first-episode psychosis and its relationship to treatment response.

Prior functional magnetic resonance imaging (fMRI) studies have investigated the neural mechanisms underlying cognitive control in patients with psychosis with findings of both hypo- and hyperfrontality. One factor that may contribute to inconsistent findings is the use of complex and polyfactorial tasks to investigate frontal lobe functioning. In the current study we employed a simple response conflict task during fMRI to examine differences in brain activation between patients experiencing their first-episode of psychosis (n = 33) and age- and sex-matched healthy volunteers (n = 33). We further investigated whether baseline brain activation among patients predicted changes in symptom severity and treatment response following 12 weeks of controlled antipsychotic treatment. During the task subjects were instructed to press a response button on the same side or opposite side of a circle that appeared on either side of a central fixation point. Imaging data revealed that for the contrast of opposite-side vs. same-side, patients showed significantly greater activation compared with healthy volunteers in the anterior cingulate cortex and intraparietal sulcus. Among patients, greater baseline anterior cingulate cortex, temporal-parietal junction, and superior temporal cortex activation predicted greater symptom reduction and therapeutic response following treatment. All findings remained significant after covarying for task performance. Intact performance on this relatively parsimonious task was associated with frontal hyperactivity suggesting the need for patients to utilize greater neural resources to achieve task performance comparable to healthy individuals. Moreover, frontal hyperactivity observed using a simple fMRI task may provide a biomarker for predicting treatment response in first-episode psychosis.

Engaging Patients: Models for Patient- and Family-centered Care in Radiology.

This article examines how radiologists can meet the objectives of patient- and family-centered care set forth by the National Committee for Quality Assurance (NCQA) program for primary care providers. The breadth of initiatives in radiology that can be mapped to the NCQA objectives is impressive and invites the idea of creating a similar program in radiology. ©RSNA, 2018.

Recurrence of Optimally Treated Malignant Peritoneal Mesothelioma with Cytoreduction and Heated Intraperitoneal Chemotherapy.

BACKGROUND: The prognosis for patients with diffuse malignant peritoneal mesothelioma has dramatically improved with cytoreductive surgery and intraperitoneal chemotherapy. Little is known about disease recurrence after treatment. We analyzed the time to and predictors of recurrence in a large cohort of optimally treated patients. METHODS: We examined 113 patients completing a two-stage cytoreduction and intraperitoneal chemotherapy protocol. All patients achieved optimal surgical resection with completeness of cytoreduction (CC) score ≤ 1 and were divided into two groups based on absence (Group A) or presence (Group B) of gross disease at the outset of the second operation. Predictors of disease recurrence and recurrence-free survival (RFS) were determined using Cox proportional hazard regression modeling, and estimates were obtained by using the Kaplan-Meier method. RESULTS: Forty-six percent of patients had no gross evidence of disease at the second operation; the remaining 54% were cytoreduced to CC ≤ 1 (Group B). Forty-two percent of patients developed disease recurrence with a median recurrence-free survival of 38.5 months for the cohort; 79% of these received a form of iterative treatment. There was no statistically significant difference in recurrence-free survival between Group A (median RFS: 44.6 months) and B (median RFS: 35.5 months) (log-rank test, p = 0.06). Additionally, the only variable significantly associated with RFS was male gender (hazard ratio [HR] 1.98, 95% confidence interval [CI] 1.16-3.38). CONCLUSIONS: Absence of gross disease at the second operation was not statistically protective against recurrence compared with presence of quantifiable residual disease (Group B) that was effectively cytoreduced. Long-term disease surveillance is recommended, because recurrence continues years after treatment. Where a question of recurrence arises on surveillance, males may benefit from a higher degree of suspicion.

Electron transfer in a supramolecular associate of a fullerene fragment.

Herein, we investigate the association of a fullerene fragment, hemifullerene C30H12, with an electron-donating bowl-shaped tetrathiafulvalene derivative (truxTTF). UV/Vis titrations and DFT calculations support formation of the supramolecular complex, for which an association constant of log Ka = 3.6±0.3 in CHCl3 at room temperature is calculated. Remarkably, electron transfer from truxTTF to C30H12 to form the fully charge-separated species takes place upon irradiation of the associate with light, constituting the first example in which a fullerene fragment mimics the electron-accepting behavior of fullerenes within a supramolecular complex.

Rapid, microwave-assisted perdeuteration of polycyclic aromatic hydrocarbons.

A simple and convenient method for the perdeuteration of polycyclic aromatic hydrocarbons that does not require strong acid has been developed. Using commercially available reagents, the one-step procedure provides a new route to perdeuterated derivatives of both common and exotic polycyclic aromatic hydrocarbons. Microwave irradiation of the hydrocarbons in a solution of dimethylformamide-d7 containing potassium tert-butoxide affords rapid and essentially complete H/D exchange. For example, corannulene is converted to corannulene-d10 with >98% deuterium incorporation in just 1 h of microwave irradiation in a solution of t-BuOK/DMF-d7.

Resilience to meet the challenge of addiction: psychobiology and clinical considerations.

Acute and chronic stress-related mechanisms play an important role in the development of addiction and its chronic, relapsing nature. Multisystem adaptations in brain, body, behavioral, and social function may contribute to a dysregulated physiological state that is maintained beyond the homeostatic range. In addition, chronic abuse of substances leads to an altered set point across multiple systems. Resilience can be defined as the absence of psychopathology despite exposure to high stress and reflects a person's ability to cope successfully in the face of adversity, demonstrating adaptive psychological and physiological stress responses. The study of resilience can be approached by examining interindividual stress responsibility at multiple phenotypic levels, ranging from psychological differences in the way people cope with stress to differences in neurochemical or neural circuitry function. The ultimate goal of such research is the development of strategies and interventions to enhance resilience and coping in the face of stress and prevent the onset of addiction problems or relapse.

Routine analysis and characterization of highly insoluble polycyclic aromatic compounds by direct analysis in real time mass spectrometry (DART).

Direct Analysis in Real Time (DART), is used for the first time for the routine rapid analysis of highly insoluble polycyclic aromatic compounds. Direct analysis of such compounds as solid samples under solvent-free conditions shows that DART is a powerful analytical platform capable of providing high-throughput analysis for these complex samples, requiring no special sample pre-treatment or instrument setup.

High dispersal in a frog species suggests that it is vulnerable to habitat fragmentation.

Global losses of amphibian populations are a major conservation concern and their causes have generated substantial debate. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture-recapture analysis of over 10,000 frogs in combination with genetic analysis of microsatellite loci in replicate basins. We found that frogs had exceptionally high juvenile dispersal rates (up to 62% annually) over long distances (>5km), large elevation gains (>750m) and steep inclines (36 degrees incline over 2km) that were corroborated by genetic data showing high gene flow. These findings show that dispersal is an important life-history feature of some amphibians and suggest that habitat fragmentation is a serious threat to amphibian persistence.