An injectable PEG hydrogel controlling neurotrophin-3 release by affinity peptides.

Neurotrophin-3 growth factor can improve cochlear neuron survival, and localized delivery of this protein to the round window membrane in the middle ear may be able to reverse sensorineural hearing loss. Thus, the goal of this work was to develop an injectable hydrogel delivery system that can allow localized release of neurotrophin-3 in a controlled and sustained manner. We identified a PEG hydrogel formulation that uses thiol-vinyl sulfone Michael addition for crosslinking. This injectable formulation provides elastic hydrogels with higher mechanical rigidity, better bio-adhesion and longer residence time than Poloxamer hydrogels currently being investigated clinically for hearing loss. In vivo, PEG hydrogels induce local immune responses comparable to biocompatible Poloxamer hydrogels, yet they released payloads at a ~5-fold slower rate in the subcutaneous area. Based on this injectable hydrogel formulation, we designed an affinity-based protein release system by modifying PEG hydrogels with affinity peptides specific to neurotrophin-3 proteins. We verified the sustained release of neurotrophin-3 from peptide-conjugated PEG hydrogels resulting from the reversible interaction between peptides and proteins. The rate of affinity-controlled release depends on the polymer concentrations, the affinity of peptides and the peptide-to-protein ratios. Collectively, we developed an injectable hydrogel formulation for localized delivery of neurotrophin-3, which provides affinity-controlled release and longer delivery time compared to Poloxamer hydrogels.

Regulation of adipose tissue inflammation and systemic metabolism in murine obesity by polymer implants loaded with lentiviral vectors encoding human interleukin-4.

Dysfunctional adipose tissue plays a central role in the pathogenesis of the obesity-related metabolic disease, including type 2 diabetes. Targeting adipose tissue using biopolymer implants is a novel therapeutic approach for metabolic disease. We transplanted porous poly(lactide-co-glycolide) (PLG) implants coated with human interleukin-4 (hIL-4)-expressing lentivirus into epididymal white adipose tissue (eWAT) of mice fed a high-fat diet. Tissue and systemic inflammation and metabolism were studied with flow cytometry, immunohistochemistry, quantitative real-time polymerase chain reaction, adipose tissue histology, and in vivo glucose tolerance testing at 2 and 10 weeks of a high-fat diet. PLG implants carrying hIL-4-expressing lentivirus implanted into epididymal white adipose tissue of mice-regulated adipose tissue inflammation, including increased CD3+ CD4+ T-cell frequency, increased eWAT adipocyte hypertrophy, and decreased FASN and ATGL expression, along with reduced fasting blood glucose levels. These effects were observed in early obesity but were not maintained in established obesity. Local delivery of bioimplants loaded with cytokine-expressing lentivirus vectors to adipose tissue influences tissue inflammation and systemic metabolism in early obesity. Further study will be required to show more durable metabolic effects. These data demonstrate that polymer biomaterials implanted into adipose tissue have the potential to modulate local tissue and systemic inflammation and metabolism.

Human lung organoids develop into adult airway-like structures directed by physico-chemical biomaterial properties.

Tissues derived from human pluripotent stem cells (hPSCs) often represent early stages of fetal development, but mature at the molecular and structural level when transplanted into immunocompromised mice. hPSC-derived lung organoids (HLOs) transplantation has been further enhanced with biomaterial scaffolds, where HLOs had improved tissue structure and cellular differentiation. Here, our goal was to define the physico-chemical biomaterial properties that maximally enhanced transplant efficiency, including features such as the polymer type, degradation, and pore interconnectivity of the scaffolds. We found that transplantation of HLOs on microporous scaffolds formed from poly (ethylene glycol) (PEG) hydrogel scaffolds inhibit growth and maturation, and the transplanted HLOs possessed mostly immature lung progenitors. On the other hand, HLOs transplanted on poly (lactide-co-glycolide) (PLG) scaffolds or polycaprolactone (PCL) led to tube-like structures that resembled both the structure and cellular diversity of an adult airway. Our data suggests that scaffold pore interconnectivity and polymer degradation contributed to the maturation, and we found that the size of the airway structures and the total size of the transplanted tissue was influenced by the material degradation rate. Collectively, these biomaterial platforms provide a set of tools to promote maturation of the tissues and to control the size and structure of the organoids.

Microporous scaffolds support assembly and differentiation of pancreatic progenitors into ß-cell clusters.

Human pluripotent stem cells (hPSCs) represent a promising cell source for the development of ß-cells for use in therapies for type 1 diabetes. Current culture approaches provide signals to mimic a temporal control of organogenesis to drive the differentiation towards ß-cells. However, spatial control may represent an opportunity to improve the efficiency and manufacturing of ß-cells. Herein, we adapted the current culture systems to microporous biomaterials with the hypothesis that the pores can guide the assembly of pancreatic progenitors into clusters of defined size that can influence maturation. The scaffold culture allowed hPSC-derived pancreatic progenitors to form clusters at a consistent size as cells differentiated. By modulating the scaffold pore sizes, we observed 250-425 µm pore size scaffold cultures augmented insulin expression and key ß-cell maturation markers compared to cells cultured in suspension. Furthermore, when compared to suspension cultures, the scaffold culture showed increased insulin secretion in response to glucose stimulus indicating the development of functional ß-cells. In addition, scaffolds facilitated cell-cell interactions enabled by the scaffold design and supported cell-mediated matrix deposition of extracellular matrix (ECM) proteins associated with the basement membrane of islet cells. We further investigated the influence of ECM on cell development by incorporating an ECM matrix on the scaffold prior to cell seeding; however, their presence did not further enhance maturation. These results suggest the microporous scaffold culture provides a conducive environment that drives in vitro differentiation of hPSC-derived insulin-producing glucose-responsive ß-cells and demonstrates the feasibility of these scaffolds as a biomanufacturing platform. STATEMENT OF SIGNIFICANCE: Cell therapy for diabetes is a promising strategy, yet generating limitless insulin-producing mature ß-cells from human pluripotent stem cells (hPSCs) remains a challenge. Current hPSC differentiation methods involve media containing signals to drive maturation toward ß-cells and spontaneous cluster formation. Herein, we sought to provide spatial cues to guide assembly of cells into 3D structures by culture within the pores of a microporous scaffold. The scaffolds direct cell-cell interactions within the pores and provide a support for cell-mediated matrix deposition that collectively creates a niche to promote functional hPSC-derived ß-cell clusters. These scaffolds for 3D culture may contribute to hPSC differentiation methods for the generation of ß-cells that can treat patients with diabetes.

It's All in the Delivery: Designing Hydrogels for Cell and Non-viral Gene Therapies.

Hydrogels provide a regenerative medicine platform with their ability to create an environment that supports transplanted or endogenous infiltrating cells and enables these cells to restore or replace the function of tissues lost to disease or trauma. Furthermore, these systems have been employed as delivery vehicles for therapeutic genes, which can direct and/or enhance the function of the transplanted or endogenous cells. Herein, we review recent advances in the development of hydrogels for cell and non-viral gene delivery through understanding the design parameters, including both physical and biological components, on promoting transgene expression, cell engraftment, and ultimately cell function. Furthermore, this review identifies emerging opportunities for combining cell and gene delivery approaches to overcome challenges to the field.

Evaluation of encapsulating and microporous nondegradable hydrogel scaffold designs on islet engraftment in rodent models of diabetes.

Islet transplantation is a promising therapeutic option for type 1 diabetes mellitus, yet the current delivery into the hepatic portal vasculature is limited by poor engraftment. Biomaterials have been used as a means to promote engraftment and function at extrahepatic sites, with strategies being categorized as encapsulation or microporous scaffolds that can either isolate or integrate islets with the host tissue, respectively. Although these approaches are typically studied separately using distinct material platforms, herein, we developed nondegradable polyethylene glycol (PEG)-based hydrogels for islet encapsulation or as microporous scaffolds for islet seeding to compare the initial engraftment and function of islets in syngeneic diabetic mice. Normoglycemia was restored with transplantation of islets within either encapsulating or microporous hydrogels containing 700 islet equivalents (IEQ), with transplantation on microporous hydrogels producing lower blood glucose levels at earlier times. A glucose challenge test at 1 month after transplant indicated that encapsulated islets had a delay in glucose-stimulated insulin secretion, whereas microporous hydrogels restored normoglycemia in times consistent with native pancreata. Encapsulated islets remained isolated from the host tissue, whereas the microporous scaffolds allowed for revascularization of the islets after transplant. Finally, we compared the inflammatory response after transplantation for the two systems and noted that microporous hydrogels had a substantially increased presence of neutrophils. Collectively, these findings suggest that both encapsulation and microporous PEG scaffold designs allow for stable engraftment of syngeneic islets and the ability to restore normoglycemia, yet the architecture influences islet function and responsiveness after transplantation.

Gelation chemistries for the encapsulation of nanoparticles in composite gel microparticles for lung imaging and drug delivery.

The formation of 10-40 µm composite gel microparticles (CGMPs) comprised of ∼100 nm drug containing nanoparticles (NPs) in a poly(ethylene glycol) (PEG) gel matrix is described. The CGMP particles enable targeting to the lung by filtration from the venous circulation. UV radical polymerization and Michael addition polymerization reactions are compared as approaches to form the PEG matrix. A fluorescent dye in the solid core of the NP was used to investigate the effect of reaction chemistry on the integrity of encapsulated species. When formed via UV radical polymerization, the fluorescence signal from the NPs indicated degradation of the encapsulated species by radical attack. The degradation decreased fluorescence by 90% over 15 min of UV exposure. When formed via Michael addition polymerization, the fluorescence was maintained. Emulsion processing using controlled shear stress enabled control of droplet size with narrow polydispersity. To allow for emulsion processing, the gelation rate was delayed by adjusting the solution pH. At a pH = 5.4, the gelation occurred at 3.5 h. The modulus of the gels was tuned over the range of 5 to 50 kPa by changing the polymer concentration between 20 and 70 vol %. NP aggregation during polymerization, driven by depletion forces, was controlled by the reaction kinetics. The ester bonds in the gel network enabled CGMP degradation. The gel modulus decreased by 50% over 27 days, followed by complete gel degradation after 55 days. This permits ultimate clearance of the CGMPs from the lungs. The demonstration of uniform delivery of 15.8 ± 2.6 µm CGMPs to the lungs of mice, with no deposition in other organs, is shown, and indicates the ability to concentrate therapeutics in the lung while avoiding off-target toxic exposure.

Detection of pancreatic tumors, image quality, and radiation dose during the pancreatic parenchymal phase: effect of a low-tube-voltage, high-tube-current CT technique--preliminary results.

PURPOSE: To intraindividually compare a low-tube-voltage (80 kVp), high-tube-current (675 mA) computed tomographic (CT) technique with a high-tube-voltage (140 kVp) CT protocol for the detection of pancreatic tumors, image quality, and radiation dose during the pancreatic parenchymal phase. MATERIALS AND METHODS: This prospective, single-center, HIPAA-compliant study was approved by the institutional review board, and written informed consent was obtained. Twenty-seven patients (nine men, 18 women; mean age, 64 years) with 23 solitary pancreatic tumors underwent dual-energy CT. Two imaging protocols were used: 140 kVp and 385 mA (protocol A) and 80 kVp and 675 mA (protocol B). For both protocols, the following variables were compared during the pancreatic parenchymal phase: contrast enhancement for the aorta, the pancreas, and the portal vein; pancreas-to-tumor contrast-to-noise ratio (CNR); noise; and effective dose. Two blinded, independent readers qualitatively scored the two data sets for tumor detection and image quality. Random-effect analysis of variance tests were used to compare differences between the two protocols. RESULTS: Compared with protocol A, protocol B yielded significantly higher contrast enhancement for the aorta (508.6 HU vs 221.5 HU, respectively), pancreas (151.2 HU vs 67.0 HU), and portal vein (189.7 HU vs 87.3 HU), along with a greater pancreas-to-tumor CNR (8.1 vs 5.9) (P < .001 for all comparisons). No statistically significant difference in tumor detection was observed between the two protocols. Although standard deviation of image noise increased with protocol B (11.5 HU vs 18.6 HU), this protocol significantly reduced the effective dose (from 18.5 to 5.1 mSv; P < .001). CONCLUSION: A low-tube-voltage, high-tube-current CT technique has the potential to improve the enhancement of the pancreas and peripancreatic vasculature, improve tumor conspicuity, and reduce patient radiation dose during the pancreatic parenchymal phase.

Gadoxetate disodium-enhanced magnetic resonance cholangiography for the noninvasive detection of an active bile duct leak after laparoscopic cholecystectomy.

We report a case of an endoscopically confirmed biliary leak of the common hepatic duct after laparoscopic cholecystectomy that was prospectively diagnosed on gadoxetate disodium-enhanced magnetic resonance cholangiography. Whereas dynamic contrast-enhanced magnetic resonance images during the early vascular phases helped to rule out the causes of possible complications such as seroma, hematoma, or abdominal abscess, delayed hepatobiliary phase imaging was crucial for unequivocal diagnosis and location of the biliary leak. The diagnosis prompted therapeutic endoscopic retrograde cholangiography whereby a polytetrafluoroethylene-covered nitinol stent graft was successfully placed to repair the biliary injury.

Low-tube-voltage, high-tube-current multidetector abdominal CT: improved image quality and decreased radiation dose with adaptive statistical iterative reconstruction algorithm--initial clinical experience.

PURPOSE: To investigate whether an adaptive statistical iterative reconstruction (ASIR) algorithm improves the image quality at low-tube-voltage (80-kVp), high-tube-current (675-mA) multidetector abdominal computed tomography (CT) during the late hepatic arterial phase. MATERIALS AND METHODS: This prospective, single-center HIPAA-compliant study was institutional review board approved. Informed patient consent was obtained. Ten patients (six men, four women; mean age, 63 years; age range, 51-77 years) known or suspected to have hypervascular liver tumors underwent dual-energy 64-section multidetector CT. High- and low-tube-voltage CT images were acquired sequentially during the late hepatic arterial phase of contrast enhancement. Standard convolution FBP was used to reconstruct 140-kVp (protocol A) and 80-kVp (protocol B) image sets, and ASIR (protocol C) was used to reconstruct 80-kVp image sets. The mean image noise; contrast-to-noise ratio (CNR) relative to muscle for the aorta, liver, and pancreas; and effective dose with each protocol were assessed. A figure of merit (FOM) was computed to normalize the image noise and CNR for each protocol to effective dose. Repeated-measures analysis of variance with Bonferroni adjustment for multiple comparisons was used to compare differences in mean CNR, image noise, and corresponding FOM among the three protocols. The noise power spectra generated from a custom phantom with each protocol were also compared. RESULTS: When image noise was normalized to effective dose, protocol C, as compared with protocols A (P = .0002) and B (P = .0001), yielded an approximately twofold reduction in noise. When the CNR was normalized to effective dose, protocol C yielded significantly higher CNRs for the aorta, liver, and pancreas than did protocol A (P = .0001 for all comparisons) and a significantly higher CNR for the liver than did protocol B (P = .003). Mean effective doses were 17.5 mSv +/- 0.6 (standard error) with protocol A and 5.1 mSv +/- 0.3 with protocols B and C. Compared with protocols A and B, protocol C yielded a small but quantifiable noise reduction across the entire spectrum of spatial frequencies. CONCLUSION: Compared with standard FBP reconstruction, an ASIR algorithm improves image quality and has the potential to decrease radiation dose at low-tube-voltage, high-tube-current multidetector abdominal CT during the late hepatic arterial phase.

Characterization of adrenal lesions: comparison of 2D and 3D dual gradient-echo MR imaging at 3 T--preliminary results.

PURPOSE: To retrospectively compare a two-dimensional (2D) and a three-dimensional (3D) technique for in-phase (IP) and opposed-phase (OP) single-breath-hold 3-T magnetic resonance (MR) imaging in the characterization of adrenal lesions, with histopathologic confirmation, computed tomographic findings, or imaging follow-up for a minimum of 6 months used as the reference standard. MATERIALS AND METHODS: This retrospective HIPAA-compliant study was approved by institutional review board, and a waiver of informed consent was obtained. Thirty-four patients (mean age, 57 years) with 37 adrenal lesions underwent 3-T adrenal MR imaging with both 2D and 3D single-breath-hold dual gradient-echo (GRE) MR sequences. Signal intensity (SI) index and adrenal-to-spleen, adrenal-to-liver, and adrenal-to-muscle SI ratios for each lesion were compared between the two techniques by using repeated-measures analysis of variance. The area under the receiver operating characteristic curve (AUC) for each evaluation method was determined, with retrospective selection of suggested thresholds. RESULTS: For the 2D and 3D techniques, the mean SI index and SI ratios were significantly different between adenomas and nonadenomas (P < .05), except for the adrenal-to-liver SI ratio with the 2D technique and the adrenal-to-muscle SI ratio with both techniques. For all evaluation methods, the AUCs were higher, although not statistically significant, for the 3D technique. The two techniques exploited different suggested thresholds for discriminating adenomas from nonadenomas. CONCLUSION: Adrenal adenomas can be readily differentiated from nonadenomas at 3-T MR imaging with either a 2D or 3D single-breath-hold dual GRE MR technique. Depending on the acquisition technique, different suggested thresholds need to be selected for various evaluation methods.

Racial and ethnic disparities in cancer pain management.

This study explored the ways in which racially and ethnically diverse patients differ in their perceptions of the cancer pain experience, barriers to treatment, and satisfaction with treatment. This cross-sectional descriptive study was conducted at four cancer treatment centers and one cancer clinic in the southeastern United States and included 66 White, African-American, Latino, and American Indian cancer patients experiencing pain related to disease or disease progression. Pain Management Index (PMI) scores were calculated and subjects provided responses to the Cancer Pain Experience questionnaire, the Barriers Questionnaire, and a modified American Pain Society Satisfaction Survey. African-Americans reported a low PMI score. Whites reported the lowest mean level of agreement with all statements about barriers to pain relief. Addressing differences in patient beliefs about what constitutes successful pain treatment and treatment satisfaction, caregiver behaviors, and system characteristics might improve the quality of care and possibly reduce the mortality of cancer patients with pain.

Tailoring cognitive-behavioral treatment for cancer pain.

Though it has been shown that cancer patients report cognitive, behavioral, and physiologic responses to pain, little attention has been paid to the benefits of cognitive-behavioral therapy (CBT) protocols tailored to patient characteristics. To determine whether a profile-tailored CBT treatment program was more effective than either standard CBT or usual care in changing outcomes for patients with cancer-related pain, 131 patients receiving treatment at four sites were randomly assigned to standard CBT, profile-tailored CBT, or usual care. CBT patients attended five 50-minute treatment sessions. When compared to standard CBT patients, profile-tailored CBT patients experienced substantial improvement from baseline to immediately post-intervention in worst pain, least pain, less interference of pain with sleep, and less confusion. From baseline to one-month post-intervention, profile-tailored patients saw greater improvement in less interference of pain with activities, walking, relationships, and sleep; less composite pain interference; and less mobility and confusion symptom distress. Standard CBT and usual care patients experienced little change. Compared to profile-tailored CBT patients, standard CBT patients showed greater improvement at six-months post-intervention with less average pain, less pain now, better bowel patterns, lower summary symptom distress, better mental quality of life, and greater improvement in Karnofsky performance status; usual care patients showed little change. More research is needed to refine the matching of cognitive-behavioral treatments to psychophysiologic patient profiles, and to determine a treatment period that does not burden those patients too fatigued to participate in a five-week program. Delivery of CBT by home visits, phone, or Internet needs to be explored further.

Is patient satisfaction a legitimate outcome of pain management?

Though many studies have measured patient satisfaction with pain management using the American Pain Society (APS) Satisfaction Survey or its variants, little is known about the relationship among the survey items, or whether items relate to satisfaction at all. In an effort to refine the measurement of patient satisfaction, a modified version of the APS survey, which was given to 787 patients as part of a study of postoperative pain management in six community hospitals, was subjected to principal components analysis to determine the survey's empirical structure. Correlations among the five components found were low; a weak relationship (r = -0.24) was discovered between pain intensity and satisfaction. A heuristic model estimated by structural equations analysis yielded additional insights. Though many items thought to influence patient satisfaction were not closely related to patient-reported satisfaction, they indicate important clinical factors relevant to quality of care, and thus, to continuing quality improvement (CQI) efforts. Results suggest that satisfaction was influenced by effectiveness of medication, independent of pain intensity, and by communication. Pain severity ratings near the time satisfaction was measured were more influential than earlier ratings.