Retrospective Outcomes of a New Acupuncture Service at a Comprehensive Cancer Center.

Introduction: Among cancer centers, patients' interest in acupuncture is growing, in addition to clinical research in the intervention. Their National Cancer Institute-designated comprehensive cancer center piloted an acupuncture service. Their aim was to assess whether acupuncture impacted patient self-reported symptoms as delivered clinically and discuss their implementation strategy. Methods: Patients undergoing acupuncture at a comprehensive cancer center from June 2019 to March 2020 were asked to complete a modified Edmonton Symptom Assessment Scale (ESAS) before and after each session. The authors evaluated symptom changes after acupuncture in both outpatient and inpatient settings. A change of ≥1 U, on the 0-10 scale, was considered clinically significant. Results: Three hundred and nine outpatient and 394 inpatient acupuncture sessions were provided to patients at the comprehensive cancer center during this period, of which surveys from 186 outpatient (34 patients) and 124 inpatient (57 patients) sessions were available for analysis. The highest pretreatment symptoms reported by outpatients were neuropathy (5.78), pain (5.58), and tiredness (5.59). Outpatients receiving acupuncture reported clinically significant improvements in pain (ESAS score change of -2.97), neuropathy (-2.68), decreased lack of well-being (-2.60), tiredness (-1.85), nausea (-1.83), anxiety (-1.56), activities of daily living issues (-1.32), depression (-1.23), anorexia (-1.19), insomnia (-1.14), and shortness of breath (-1.14). The most severe pretreatment symptoms reported by inpatients were pain (6.90), insomnia (6.16), and constipation (5.44). Inpatients receiving acupuncture reported clinically significant improvements in anxiety (-3.69), nausea (-3.61), insomnia (-3.26), depression (-2.98), pain (-2.77), neuropathy (-2.68), anorexia (-2.20), constipation (-1.95), and diarrhea (-1.26). Conclusion: Both outpatient and inpatient participants in this pilot acupuncture program reported clinically significant improvements in symptoms after a single acupuncture treatment. Some differences between the outpatient and inpatient settings warrant further investigation.

Are NCI Cancer Centers Providing Adolescents and Young Adults With Cancer Focused Clinical Services? A National Survey.

BACKGROUND: This study sought to evaluate the current services and delivery models of adolescent and young adult oncology (AYAO)-specific programs at NCI-designated Cancer Centers (NCI-CCs). PATIENTS AND METHODS: NCI, academic, and community cancer centers were electronically sent surveys from October to December 2020 and administered via REDCap. RESULTS: Survey responses were received from 50 of 64 (78%) NCI-CCs, primarily completed by pediatric oncologists (53%), adult oncologists (11%), and social workers (11%). Half (51%) reported an existing AYAO program, with most (66%) started within the past 5 years. Although most programs combined medical and pediatric oncology (59%), 24% were embedded within pediatrics alone. Most programs saw patients aged 15 (55%) to 39 years (66%) mainly via outpatient clinic consultation (93%). Most centers reported access to a range of medical oncology and supportive services, but dedicated services specifically for adolescent and young adults (AYAs) were available at a much lower extent, such as social work (98% vs 58%) and psychology (95% vs 54%). Although fertility preservation was offered by all programs (100%), only two-thirds of NCI centers (64%) reported providing sexual health services to AYAs. Most NCI-CCs (98%) were affiliated with a research consortium, and a lesser extent (73%) reported collaboration between adult and pediatric researchers. Nearly two-thirds (60%) reported that AYA oncology care was important/very important to their respective institution and reported providing good/excellent care to AYAs with cancer (59%), but to a lesser extent reported good/excellent research (36%), sexual health (23%), and education of staff (21%). CONCLUSIONS: Results of this first-ever national survey to assess AYAO programs showed that only half of NCI-CCs report having a dedicated AYAO program, and that areas of improvement include staff education, research, and sexual health services for patients.

Associations between symptoms with healthcare utilization and death in advanced cancer patients.

INTRODUCTION: There is limited data about assessments that are associated with increased utilization of medical services among advanced oncology patients (AOPs). We aimed to identify factors related to healthcare utilization and death in AOP. METHODS: AOPs at a comprehensive cancer center were enrolled in a Center for Medicare and Medicaid Innovation program. Participants completed the Edmonton Symptom Assessment Scale (ESAS) and the Functional Assessment of Cancer Therapy-General (FACT-G) scale. We examined factors associated with palliative care (PC), acute care (AC), emergency room (ER), hospital admissions (HA), and death. RESULTS: In all, 817 AOPs were included in these analyses with a median age of 69. They were generally female (58.7%), white (61.4%), stage IV (51.6%), and represented common cancers (31.5% GI, 25.2% thoracic, 14.3% gynecologic). ESAS pain, anxiety, and total score were related to more PC visits (B=0.31, 95% CI [0.21, 0.40], p<0.001; B=0.24 [0.12, 0.36], p<0.001; and B=0.038 [0.02, 0.06], p=0.001, respectively). Total FACT-G score and physical subscale were related to total PC visits (B=-0.021 [-0.037, -0.006], p=0.008 and B=-0.181 [-0.246, -0.117], p<0.001, respectively). Lower FACT-G social subscale scores were related to more ER visits (B=-0.03 [-0.53, -0.004], p=0.024), while increased tiredness was associated with fewer AC visits (B=-0.039 [-0.073, -0.006], p=0.023). Higher total ESAS scores were related to death within 30 days (OR=0.87 [0.76, 0.98], p=0.027). CONCLUSIONS: The ESAS and FACT-G assessments were linked to PC and AC visits and death. These assessments may be useful for identifying AOPs that would benefit from routine PC.

The perspectives of oncology healthcare providers on the role of palliative care in a comprehensive cancer center.

BACKGROUND: Palliative care (PC) is an essential part of oncologic care, but its optimal role within a cancer center remains unclear. This study examines oncology healthcare providers' perspectives about the role of PC at a comprehensive cancer center (CCC). METHODS: Physicians, nurses, and other oncology healthcare providers at a CCC were surveyed for their opinions about the role of inpatient and outpatient PC, preferences for PC services, and barriers to referral. Chi-squared tests and multiple regression analyses were performed to explore associations. RESULTS: We received 137/221 completed questionnaires (61% response rate). Respondents were generally female (78%), had ≤ 10 years of service (69%), and included physicians (32%), nurses (32%), and advanced practice providers (17%). Most respondents (82%) agreed that more patients could benefit from PC. They also agreed that PC is beneficial for both outpatient and inpatient management of complex pain (96 and 88%), complex symptoms (84 and 74%), and advanced cancer patients (80 and 64%). Transition to hospice (64 vs. 42%, p = 0.007) and goals of care (62 vs. 49%, p = 0.011) provided by PC services were more valued by respondents for the inpatient than for the outpatient setting. Barriers to utilizing PC included lack of availability, unsure of when to refer, and poor communication. The majority of respondents (83%) preferred a cancer focused PC team to provide high-quality care. CONCLUSIONS: Overall, the majority of oncology health care providers believe that more patients could benefit from PC, but opinions vary regarding the roles of inpatient and outpatient PC. Barriers and areas for improvement include availability, referral process, and improved communication.

Protein-PAINT: Superresolution microscopy with signaling proteins.

Superresolution techniques have advanced our understanding of complex cellular structures and processes but require the attachment of fluorophores to targets through tags or antibodies, which can be bulky and result in underlabeling. To overcome these limitations, we developed a technique to visualize the nanoscale binding locations of signaling proteins by taking advantage of their native interaction domains. Here, we demonstrated that pPAINT (protein point accumulation in nanoscale topography) is a new, single-molecule localization microscopy (SMLM) technique and used it to investigate T cell signaling by visualizing the Src homology 2 (SH2) domain, which is common in signaling molecules. When SH2 domain-containing proteins relocate to the plasma membrane, the domains selectively, transiently, and reversibly bind to preferred phosphorylated tyrosine residues on receptors. This transient binding yields the stochastic blinking events necessary for SMLM when observed with total internal reflection microscopy and enables quantification of binding coefficients in intact cells. We used pPAINT to reveal the binding sites of several T cell receptor-proximal signaling molecules, including Zap70, PI3K, Grb2, Syk, Eat2, and SHP2, and showed that the probes could be multiplexed. We showed that the binding half-life of the tandem SH2 domain of PI3K correlated with binding site cluster size at the immunological synapses of T cells, but that longer binding lifetimes were associated with smaller clusters for the monovalent SH2 domain of Eat2. These results demonstrate the potential of pPAINT for investigating phosphotyrosine-mediated signaling processes at the plasma membrane.

The porcine accessory carpal bone as a model for biologic joint replacement for trapeziometacarpal osteoarthritis.

Given its complex shape and relatively small size, the trapezium surface at the trapeziometacarpal (TMC) joint is a particularly attractive target for anatomic biologic joint resurfacing, especially given its propensity to develop osteoarthritis, and the limited and sub-optimal treatment options available. For this to advance to clinical translation, however, an appropriate large animal model is required. In this study, we explored the porcine accessory carpal bone (ACB) as a model for the human trapezium. We characterized ACB anatomy, geometry, joint and tissue-scale mechanics, and composition across multiple donors. We showed that the ACB is similar both in size, and in the saddle shape of the main articulating surface to the human trapezium, and that loads experienced across each joint are similar. Using this information, we then devised a fabrication method and workflow to produce patient-specific tissue-engineered replicas based on CT scans, and showed that when such replicas are implanted orthotopically in an ex vivo model, normal loading is restored. Data from this study establish the porcine ACB as a model system in which to evaluate function of engineered living joint resurfacing strategies. STATEMENT OF SIGNIFICANCE: Biologic joint resurfacing, or the replacement of a joint with living tissue as opposed to metal and plastic, is the holy grail of orthopaedic tissue engineering. However, despite marked advances in engineering native-like osteochondral tissues and in matching patient-specific anatomy, these technologies have not yet reached clinical translation. Given its propensity for developing osteoarthritis, as well as its small size and complex shape, the trapezial surface of the trapeziometacarpal joint at the base of the thumb presents a unique opportunity for pursuing a biologic joint resurfacing strategy. This work establishes the porcine accessory carpal bone as an animal model for the human trapezium and presents a viable test-bed for evaluating the function of engineered living joint resurfacing strategies.

K-Neighbourhood Analysis: A Method for Understanding SMLM Images as Compositions of Local Neighbourhoods.

Single molecule localisation microscopy (SMLM) is a powerful tool that has revealed the spatial arrangement of cell surface signalling proteins, producing data of enormous complexity. The complexity is partly driven by the convolution of technical and biological signal components, and partly by the challenge of pooling information across many distinct cells. To address these two particular challenges, we have devised a novel algorithm called K-neighbourhood analysis (KNA), which emphasises the fact that each image can also be viewed as a composition of local neighbourhoods. KNA is based on a novel transformation, spatial neighbourhood principal component analysis (SNPCA), which is defined by the PCA of the normalised K-nearest neighbour vectors of a spatially random point pattern. Here, we use KNA to define a novel visualisation of individual images, to compare within and between groups of images and to investigate the preferential patterns of phosphorylation. This methodology is also highly flexible and can be used to augment existing clustering methods by providing clustering diagnostics as well as revealing substructure within microclusters. In summary, we have presented a highly flexible analysis tool that presents new conceptual possibilities in the analysis of SMLM images.

Genomic evidence for reinfection with SARS-CoV-2: a case study.

BACKGROUND: The degree of protective immunity conferred by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently unknown. As such, the possibility of reinfection with SARS-CoV-2 is not well understood. We describe an investigation of two instances of SARS-CoV-2 infection in the same individual. METHODS: A 25-year-old man who was a resident of Washoe County in the US state of Nevada presented to health authorities on two occasions with symptoms of viral infection, once at a community testing event in April, 2020, and a second time to primary care then hospital at the end of May and beginning of June, 2020. Nasopharyngeal swabs were obtained from the patient at each presentation and twice during follow-up. Nucleic acid amplification testing was done to confirm SARS-CoV-2 infection. We did next-generation sequencing of SARS-CoV-2 extracted from nasopharyngeal swabs. Sequence data were assessed by two different bioinformatic methodologies. A short tandem repeat marker was used for fragment analysis to confirm that samples from both infections came from the same individual. FINDINGS: The patient had two positive tests for SARS-CoV-2, the first on April 18, 2020, and the second on June 5, 2020, separated by two negative tests done during follow-up in May, 2020. Genomic analysis of SARS-CoV-2 showed genetically significant differences between each variant associated with each instance of infection. The second infection was symptomatically more severe than the first. INTERPRETATION: Genetic discordance of the two SARS-CoV-2 specimens was greater than could be accounted for by short-term in vivo evolution. These findings suggest that the patient was infected by SARS-CoV-2 on two separate occasions by a genetically distinct virus. Thus, previous exposure to SARS-CoV-2 might not guarantee total immunity in all cases. All individuals, whether previously diagnosed with COVID-19 or not, should take identical precautions to avoid infection with SARS-CoV-2. The implications of reinfections could be relevant for vaccine development and application. FUNDING: Nevada IDEA Network of Biomedical Research, and the National Institute of General Medical Sciences (National Institutes of Health).

Fabrication and maturation of integrated biphasic anatomic mesenchymal stromal cell-laden composite scaffolds for osteochondral repair and joint resurfacing.

Articular cartilage injury can lead to joint-wide erosion and the early onset of osteoarthritis. To address this, we recently developed a rapid fabrication method to produce patient-specific engineered cartilage tissues to replace an entire articular surface. Here, we extended that work by coupling a mesenchymal stromal cell-laden hydrogel (methacrylated hyaluronic acid) with the porous polycaprolactone (PCL) bone integrating phase and assessed the composition and mechanical performance of these constructs over time. To improve initial construct stability, PCL/hydrogel interface parameters were first optimized by varying PCL pretreatment (with sodium hydroxide before ethanol) before hydrogel infusion. Next, cylindrical osteochondral constructs were formed and cultured in media containing transforming growth factor ß3 for up to 8 weeks, with constructs evaluated for viability, histological features, and biochemical content. Mechanical properties were also assessed in axial compression and via an interface shear strength assay. Results showed that the fabrication process was compatible with cell viability, and that construct biochemical content and mechanical properties increased with time. Interestingly, compressive properties peaked at 5 weeks, while interfacial shear properties continued to improve beyond this time point. Finally, these fabrication methods were combined with a custom mold developed from limb-specific computed tomography imaging data to create an anatomic implantable cell-seeded biologic joint surface, which showedmaturation similar to the osteochondral cylinders. Future work will apply these advances in large animal models of critically sized osteochondral defects to study repair and whole joint resurfacing.

Impact of Contaminated Blood Cultures on Children, Families, and the Health Care System.

BACKGROUND: Contaminated blood cultures pose a significant burden. We sought to determine the impact of contaminated peripheral blood cultures on patients, families, and the health care system. METHODS: In this retrospective case-control study from January 1, 2014, to December 31, 2017, we compared the hospital course, return visits and/or admissions, charges, and length of stay of patients with contaminated peripheral blood cultures (case patients) with those of patients with negative cultures (controls). Patients were categorized into those evaluated and discharged from the emergency department (ED) (ED patients) and those who were hospitalized (inpatients). RESULTS: A total of 104 ED case patients were matched with 208 ED control patients. A total of 343 case inpatients were matched with 686 inpatient controls. There was no significant difference between case and control patient demographics, ED, or hospital course at presentation. Fifty-five percent of discharged ED patients returned to the hospital for evaluation and/or admission versus 4% of controls. There was a significant (P < .0001) increase in repeat blood cultures (43% vs 1%), consultations obtained (21% vs 2%), cerebrospinal fluid studies (10% vs 0%), and antibiotic administration (27% vs 1%) in ED patients compared with controls. Each ED patient requiring revisit to the hospital incurred, on average, $4660 in additional charges. There was a significant (P < .04) increase in repeat blood cultures (57% vs 7%), consultations obtained (35% vs 28%), broadening of antibiotic coverage (18% vs 11%), median length of stay (75 vs 64 hours), and median laboratory charges ($3723 vs $3296) in case inpatients compared with controls. CONCLUSIONS: Contaminated blood cultures result in increased readmissions, testing and/or procedures, length of stay, and hospital charges in children.

T Cell Membrane Heterogeneity Aids Antigen Recognition and T Cell Activation.

T cells are critical for co-ordinating the immune response. T cells are activated when their surface T cell receptors (TCRs) engage cognate antigens in the form of peptide-major histocompatibility complexes (pMHC) presented on the surface of antigen presenting cells (APCs). Large changes in the contact interface between T cells and APCs occur over the course of tens of minutes from the initial contact to the formation of a large-scale junction between the two cells. The mature junction between a T cell and APC is known as the immunological synapse, and this specialized plasma membrane structure is the major platform for TCR signaling. It has long been known that the complex organization of signaling molecules at the synapse is critical for appropriate activation of T cells, but within the last decade advances in microscopy have opened up investigation into the dynamics of T cell surface topology in the immune synapse. From mechanisms mediating the initial contact between T cells and APCs to roles in the organization of molecules in the mature synapse, these studies have made it increasingly clear that local membrane topology has a large impact on signaling processes. This review focuses on the functional consequences of the T cells' highly dynamic and heterogeneous membrane, in particular, how membrane topology leads to the reorganization of membrane proteins on the T cell surface.

Inferior clinical outcomes after femur fracture in the obese are potentially preventable.

INTRODUCTION: Obese patients with operative orthopedic trauma have increased risk of adverse outcomes, although the mechanisms accounting for the relationship remain unknown. This study examines the effect of body mass index (BMI) on outcomes after femur fracture fixation, and explores the mediating effects of pathophysiologic factors and clinical management. METHODS: A retrospective chart review was performed of adult patients with femur fractures undergoing surgical fixation at a Level 1 trauma center from 2010 to 2016. Demographics, Injury Severity Score (ISS), Glasgow Coma Scale (GCS) and mechanism of injury (MOI) were collected along with operative data and complications. Primary outcomes were hospital length of stay (HLOS), ICU length of stay (ICU-LOS), mortality, complications, and time to mobility (time first out of bed, TFOB). Bivariate correlations and multiple regression models were used to examine the relationship between BMI and outcomes. Path analysis tested whether the relationship between BMI and clinical outcomes was mediated by differences in 1) clinical management, or 2) physiologic variables. RESULTS: Of 333 patients included, the majority were male (57.4%) with a mean age of 43.4 (22.7) years and ISS of 12.5 (6.8). Predominant MOIs were motor vehicle crashes (42.8%) and falls (34.5%). There was no association between BMI category and age, ISS, or GCS. In univariate analysis, higher BMI was linked to longer HLOS (r = .12), longer ICU-LOS (r = .15), longer TFOB, (r = .18), and higher number of complications (r = .12), p < 0.05. Controlling for age and ISS, obese patients had 6.66 times the odds of respiratory failure (p = 0.021, 95% CI 1.3,33.3) and a 3.88 odds of any complication (p = 0.020, 95% CI 1.24,12.1) compared to their normal weight counterparts. For every one point increase in BMI, time first out of bed was delayed 2.3 h (p < 0.001; 95% CI 1.08, 3.62). The effect BMI on poor outcomes was accounted for by delayed mobility (longer TFOB) in a mediation model. CONCLUSIONS: Higher BMI increases the risk of longer hospital stays and systemic complications. Mediation models indicate that the adverse clinical outcomes associated with obesity are explained by delays in mobility, an intervenable factor. Clinical strategies should be directed at early mobilization to minimize morbidity.

EAST Multicenter Trial on targeted temperature management for hanging-induced cardiac arrest.

BACKGROUND: We sought to determine the outcome of suicidal hanging and the impact of targeted temperature management (TTM) on hanging-induced cardiac arrest (CA) through an Eastern Association for the Surgery of Trauma (EAST) multicenter retrospective study. METHODS: We analyzed hanging patient data and TTM variables from January 1992 to December 2015. Cerebral performance category score of 1 or 2 was considered good neurologic outcome, while cerebral performance category score of 3 or 4 was considered poor outcome. Classification and Regression Trees recursive partitioning was used to develop multivariate predictive models for survival and neurologic outcome. RESULTS: A total of 692 hanging patients from 17 centers were analyzed for this study. Their overall survival rate was 77%, and the CA survival rate was 28.6%. The CA patients had significantly higher severity of illness and worse outcome than the non-CA patients. Of the 175 CA patients who survived to hospital admission, 81 patients (46.3%) received post-CA TTM. The unadjusted survival of TTM CA patients (24.7% vs 39.4%, p < 0.05) and good neurologic outcome (19.8% vs 37.2%, p < 0.05) were worse than non-TTM CA patients. However, when subgroup analyses were performed between those with an admission Glasgow Coma Scale score of 3 to 8, the differences between TTM and non-TTM CA survival (23.8% vs 30.0%, p = 0.37) and good neurologic outcome (18.8% vs 28.7%, p = 0.14) were not significant. Targeted temperature management implementation and post-CA management varied between the participating centers. Classification and Regression Trees models identified variables predictive of favorable and poor outcome for hanging and TTM patients with excellent accuracy. CONCLUSION: Cardiac arrest hanging patients had worse outcome than non-CA patients. Targeted temperature management CA patients had worse unadjusted survival and neurologic outcome than non-TTM patients. These findings may be explained by their higher severity of illness, variable TTM implementation, and differences in post-CA management. Future prospective studies are necessary to ascertain the effect of TTM on hanging outcome and to validate our Classification and Regression Trees models. LEVEL OF EVIDENCE: Therapeutic study, level IV; prognostic study, level III.

A Cost and Quality Analysis of Utilizing a Rectal Catheter for Medication Administration in End-of-Life Symptom Management.

Technology that can improve the ability to provide quick symptom control while decreasing the cost and burden of care could help hospice agencies deal with current hospice industry challenges. This paper describes how the use of a new rectal medication delivery technology at a large hospice in western New York has improved patient care and nursing efficiency while at the same time decreasing the cost of care.

Placental Drug Transport-on-a-Chip: A Microengineered In Vitro Model of Transporter-Mediated Drug Efflux in the Human Placental Barrier.

The current lack of knowledge about the effect of maternally administered drugs on the developing fetus is a major public health concern worldwide. The first critical step toward predicting the safety of medications in pregnancy is to screen drug compounds for their ability to cross the placenta. However, this type of preclinical study has been hampered by the limited capacity of existing in vitro and ex vivo models to mimic physiological drug transport across the maternal-fetal interface in the human placenta. Here the proof-of-principle for utilizing a microengineered model of the human placental barrier to simulate and investigate drug transfer from the maternal to the fetal circulation is demonstrated. Using the gestational diabetes drug glyburide as a model compound, it is shown that the microphysiological system is capable of reconstituting efflux transporter-mediated active transport function of the human placental barrier to limit fetal exposure to maternally administered drugs. The data provide evidence that the placenta-on-a-chip may serve as a new screening platform to enable more accurate prediction of drug transport in the human placenta.

Enhanced nutrient transport improves the depth-dependent properties of tri-layered engineered cartilage constructs with zonal co-culture of chondrocytes and MSCs.

Biomimetic design in cartilage tissue engineering is a challenge given the complexity of the native tissue. While numerous studies have generated constructs with near-native bulk properties, recapitulating the depth-dependent features of native tissue remains a challenge. Furthermore, limitations in nutrient transport and matrix accumulation in engineered constructs hinders maturation within the central core of large constructs. To overcome these limitations, we fabricated tri-layered constructs that recapitulate the depth-dependent cellular organization and functional properties of native tissue using zonally derived chondrocytes co-cultured with MSCs. We also introduced porous hollow fibers (HFs) and HFs/cotton threads to enhance nutrient transport. Our results showed that tri-layered constructs with depth-dependent organization and properties could be fabricated. The addition of HFs or HFs/threads improved matrix accumulation in the central core region. With HF/threads, the local modulus in the deep region of tri-layered constructs nearly matched that of native tissue, though the properties in the central regions remained lower. These constructs reproduced the zonal organization and depth-dependent properties of native tissue, and demonstrate that a layer-by-layer fabrication scheme holds promise for the biomimetic repair of focal cartilage defects. STATEMENT OF SIGNIFICANCE: Articular cartilage is a highly organized tissue driven by zonal heterogeneity of cells, extracellular matrix proteins and fibril orientations, resulting in depth-dependent mechanical properties. Therefore, the recapitulation of the functional properties of native cartilage in a tissue engineered construct requires such a biomimetic design of the morphological organization, and this has remained a challenge in cartilage tissue engineering. This study demonstrates that a layer-by-layer fabrication scheme, including co-cultures of zone-specific articular CHs and MSCs, can reproduce the depth-dependent characteristics and mechanical properties of native cartilage while minimizing the need for large numbers of chondrocytes. In addition, introduction of a porous hollow fiber (combined with a cotton thread) enhanced nutrient transport and depth-dependent properties of the tri-layered construct. Such a tri-layered construct may provide critical advantages for focal cartilage repair. These constructs hold promise for restoring native tissue structure and function, and may be beneficial in terms of zone-to-zone integration with adjacent host tissue and providing more appropriate strain transfer after implantation.

A microengineered model of RBC transfusion-induced pulmonary vascular injury.

Red blood cell (RBC) transfusion poses significant risks to critically ill patients by increasing their susceptibility to acute respiratory distress syndrome. While the underlying mechanisms of this life-threatening syndrome remain elusive, studies suggest that RBC-induced microvascular injury in the distal lung plays a central role in the development of lung injury following blood transfusion. Here we present a novel microengineering strategy to model and investigate this key disease process. Specifically, we created a microdevice for culturing primary human lung endothelial cells under physiological flow conditions to recapitulate the morphology and hemodynamic environment of the pulmonary microvascular endothelium in vivo. Perfusion of the microengineered vessel with human RBCs resulted in abnormal cytoskeletal rearrangement and release of intracellular molecules associated with regulated necrotic cell death, replicating the characteristics of acute endothelial injury in transfused lungs in vivo. Our data also revealed the significant effect of hemodynamic shear stress on RBC-induced microvascular injury. Furthermore, we integrated the microfluidic endothelium with a computer-controlled mechanical stretching system to show that breathing-induced physiological deformation of the pulmonary microvasculature may exacerbate vascular injury during RBC transfusion. Our biomimetic microsystem provides an enabling platform to mechanistically study transfusion-associated pulmonary vascular complications in susceptible patient populations.

Single-cell differences in matrix gene expression do not predict matrix deposition.

Mesenchymal stem cells (MSCs) display substantial cell-to-cell heterogeneity, complicating their use in regenerative medicine. However, conventional bulk assays mask this variability. Here we show that both chondrocytes and chondrogenically induced MSCs exhibit substantial mRNA expression heterogeneity. Single-molecule RNA FISH to measure mRNA expression of differentiation markers in single cells reveals that sister cell pairs have high levels of mRNA variability, suggesting that marker expression is not heritable. Surprisingly, this variability does not correlate with cell-to-cell differences in cartilage-like matrix production. Transcriptome-wide analysis suggests that no combination of markers can predict functional potential. De-differentiating chondrocytes also show a disconnect between mRNA expression of the cartilage marker aggrecan and cartilage-like matrix accumulation. Altogether, these quantitative analyses suggest that sorting subpopulations based on these markers would only marginally enrich the progenitor population for 'superior' MSCs. Our results suggest that instantaneous mRNA abundance of canonical markers is tenuously linked to the chondrogenic phenotype at the single-cell level.

Hypoxic regulation of functional extracellular matrix elaboration by nucleus pulposus cells in long-term agarose culture.

Degeneration of the intervertebral discs is strongly implicated as a cause of low back pain. Since current treatments for discogenic low back pain show poor long-term efficacy, a number of new biological strategies are being pursued. For such therapies to succeed, it is critical that they be validated in conditions that mimic the unique biochemical microenvironment of the nucleus pulposus (NP), which include low oxygen tension. Therefore, the objective of this study was to investigate the effects of oxygen tension on NP cell functional extracellular matrix elaboration in 3D culture. Bovine NP cells were encapsulated in agarose constructs and cultured for 14 or 42 days in either 20% or 2% oxygen in defined media containing transforming growth factor beta-3. At each time point, extracellular matrix composition, biomechanics, and mRNA expression of key phenotypic markers were evaluated. Results showed that while bulk mechanics and composition were largely independent of oxygen level, low oxygen promoted improved restoration of the NP phenotype, higher mRNA expression of extracellular matrix and NP specific markers, and more uniform matrix elaboration. These findings indicate that culture under physiological oxygen levels is an important consideration for successful development of cell and growth factor-based regenerative strategies for the disc.

Functional properties of bone marrow-derived MSC-based engineered cartilage are unstable with very long-term in vitro culture.

The success of stem cell-based cartilage repair requires that the regenerate tissue reach a stable state. To investigate the long-term stability of tissue engineered cartilage constructs, we assessed the development of compressive mechanical properties of chondrocyte and mesenchymal stem cell (MSC)-laden three dimensional agarose constructs cultured in a well defined chondrogenic in vitro environment through 112 days. Consistent with previous reports, in the presence of TGF-ß, chondrocytes outperformed MSCs through day 56, under both free swelling and dynamic culture conditions, with MSC-laden constructs reaching a plateau in mechanical properties between days 28 and 56. Extending cultures through day 112 revealed that MSCs did not simply experience a lag in chondrogenesis, but rather that construct mechanical properties never matched those of chondrocyte-laden constructs. After 56 days, MSC-laden constructs underwent a marked reversal in their growth trajectory, with significant declines in glycosaminoglycan content and mechanical properties. Quantification of viability showed marked differences in cell health between chondrocytes and MSCs throughout the culture period, with MSC-laden construct cell viability falling to very low levels at these extended time points. These results were not dependent on the material environment, as similar findings were observed in a photocrosslinkable hyaluronic acid (HA) hydrogel system that is highly supportive of MSC chondrogenesis. These data suggest that, even within a controlled in vitro environment that is conducive to chondrogenesis, there may be an innate instability in the MSC phenotype that is independent of scaffold composition, and may ultimately limit their application in functional cartilage repair.