Urinary MicroRNA Biomarkers of Nephrotoxicity in Macaca fascicularis.

Drug-induced kidney injury (DIKI) refers to kidney damage resulting from the administration of medications. The aim of this project was to identify reliable urinary microRNA (miRNAs) biomarkers that can be used as potential predictors of DIKI before disease diagnosis. This study quantified a panel of six miRNAs (miRs-210-3p, 423-5p, 143-3p, 130b-3p, 486-5p, 193a-3p) across multiple time points using urinary samples from a previous investigation evaluating effects of a nephrotoxicant in cynomolgus monkeys. Exosome-associated miRNA exhibited distinctive trends when compared to miRNAs quantified in whole urine, which may reflect a different urinary excretion mechanism of miRNAs than those released passively into the urine. Although further research and mechanistic studies are required to elucidate how these miRNAs regulate signaling in disease pathways, we present, for the first time, data that several miRNAs displayed strong correlations with histopathology scores, thus indicating their potential use as biomarkers to predict the development of DIKI in preclinical studies and clinical trials. Also, these findings can potentially be translated into other non-clinical species or human for the detection of DIKI.

Health Service Utilization in Adolescents Following a First Arrest: The Role of Antisocial Behavior, Callous-Unemotional Traits, and Juvenile Justice System Processing.

Previous research indicates that youth exhibiting antisocial behavior are at risk for utilizing a disproportionate amount of health services compared to youth without these problems. The present study investigates whether being processed by the juvenile justice system and showing callous-unemotional (CU) traits independently predict health service utilization (medical and mental health service use and out-of-home placement) over and above the severity of antisocial behavior across adolescence. A total of 766 participants who had been arrested for the first time in adolescence provided data at ten appointments over a period of seven years. Results showed that self-reported antisocial behavior at the time of arrest predicted increased use of most health service use types over the next seven years (i.e. medicine prescriptions, tests for sexually transmitted infections, mental health service appointments, and out-of-home placements). All except prescription medication use remained significant when controlling for justice system processing and CU traits. Further, justice system processing added significantly to the prediction of medical service appointments. Whereas CU traits were associated with mental health service appointments and out-of-home placements, these did not remain significant when controlling for severity of antisocial behavior. These findings are consistent with prior research documenting the health care costs of antisocial behavior.

Effect of gamma irradiation on the physical properties of MoS2 monolayer.

Two-dimensional transition metal dichalcogenides (2D-TMDs) have been proposed as novel optoelectronic materials for space applications due to their relatively light weight. MoS2 has been shown to have excellent semiconducting and photonic properties. Although the strong interaction of ionizing gamma radiation with bulk materials has been demonstrated, understanding its effect on atomically thin materials has scarcely been investigated. Here, we report the effect of gamma irradiation on the structural and electronic properties of a monolayer of MoS2. We perform Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) studies of MoS2, before and after gamma ray irradiation with varying doses and density functional theory (DFT) calculations. The Raman spectra and XPS results demonstrate that point defects dominate after the gamma irradiation of MoS2. DFT calculations elucidate the electronic properties of MoS2 before and after irradiation. Our work makes several contributions to the field of 2D materials research. First, our study of the electronic density of states and the electronic properties of a MoS2 monolayer irradiated by gamma rays sheds light on the properties of a MoS2 monolayer under gamma irradiation. Second, our study confirms that point defects are formed as a result of gamma irradiation. And third, our DFT calculations qualitatively suggest that the conductivity of the MoS2 monolayer may increase after gamma irradiation due to the creation of additional defect states.

Proactive and reactive aggression: Developmental trajectories and longitudinal associations with callous-unemotional traits, impulsivity, and internalizing emotions.

Research on proactive and reactive aggression has identified covariates unique to each function of aggression, but hypothesized correlates have often not been tested with consideration of developmental changes in or the overlap between the types of aggression. The present study examines the unique developmental trajectories of proactive and reactive aggression over adolescence and young adulthood and tests these trajectories' associations with key covariates: callous-unemotional (CU) traits, impulsivity, and internalizing emotions. In a sample of 1,211 justice-involved males (ages 15-22), quadratic growth models (i.e., intercepts, linear slopes, and quadratic slopes) of each type of aggression were regressed onto quadratic growth models of the covariates while controlling for the other type of aggression. After accounting for the level of reactive aggression, the level of proactive aggression was predicted by the level of CU traits. However, change in proactive aggression over time was not related to the change in any covariates. After accounting for proactive aggression, reactive aggression was predicted by impulsivity, both at the initial level and in change over time. Results support that proactive and reactive aggression are unique constructs with separate developmental trajectories and distinct covariates.

Bag-Mask Ventilation Versus Apneic Oxygenation During Tracheal Intubation in Critically Ill Adults: A Secondary Analysis of 2 Randomized Trials.

Background: Hypoxemia is common during tracheal intubation in intensive care units. To prevent hypoxemia during intubation, 2 methods of delivering oxygen between induction and laryngoscopy have been proposed: bag-mask ventilation and supplemental oxygen delivered by nasal cannula without ventilation (apneic oxygenation). Whether one of these approaches is more effective for preventing hypoxemia during intubation of critically ill patients is unknown. Methods: We performed a secondary analysis of data from 138 patients enrolled in 2, consecutive randomized trials of airway management in an academic intensive care unit. A total of 61 patients were randomized to receive bag-mask ventilation in a trial comparing bag-mask ventilation to none, and 77 patients were randomized to receive 100% oxygen at 15 L/min by nasal cannula in a trial comparing apneic oxygenation to none. Using multivariable linear regression accounting for age, body mass index, severity of illness, and oxygen saturation at induction, we compared patients assigned to bag-mask ventilation with those assigned to apneic oxygenation regarding lowest oxygen saturations from induction to 2 min after intubation. Results: Patients assigned to bag-mask ventilation and apneic oxygenation were similar at baseline. The median lowest oxygen saturation was 96% (interquartile range [IQR] 89%-100%) in the bag-mask ventilation group and 92% (IQR 84%-99%) in the apneic oxygenation group. After adjustment for prespecified confounders, bag-mask ventilation was associated with a higher lowest oxygen saturation compared to apneic oxygenation (mean difference, 4.2%; 95% confidence interval, 0.7%-7.8%; P = .02). The incidence of severe hypoxemia (oxygen saturation<80%) was 6.6% in the bag-mask ventilation group and 15.6% in the apneic oxygenation group (adjusted odds ratio, 0.33; P = .09). Conclusions: This secondary analysis of patients assigned to bag-mask ventilation and apneic oxygenation during 2 clinical trials suggests that bag-mask ventilation is associated with higher oxygen saturation during intubation compared to apneic oxygenation.

Protocolized Postextubation Respiratory Support to Prevent Reintubation: A Randomized Clinical Trial.

Rationale: Respiratory support (noninvasive ventilation or high-flow nasal cannula) applied at the time of extubation has been reported to reduce reintubation rates, but concerns regarding effectiveness have limited uptake into practice.Objectives: To determine if providing postextubation respiratory support to all patients undergoing extubation in a medical ICU would decrease the incidence of reintubation.Methods: We conducted a pragmatic, two-armed, cluster-crossover trial of adults undergoing extubation from invasive mechanical ventilation between October 1, 2017, and March 31, 2019, in the medical ICU of an academic medical center. Patients were assigned to either protocolized postextubation respiratory support (a respiratory therapist-driven protocol in which patients with suspected hypercapnia received noninvasive ventilation and patients without suspected hypercapnia received high-flow nasal cannula) or usual care (postextubation management at the discretion of treating clinicians). The primary outcome was reintubation within 96 hours of extubation.Measurements and Main Results: A total of 751 patients were enrolled. Of the 359 patients assigned to protocolized support, 331 (92.2%) received postextubation respiratory support compared with 66 of 392 patients (16.8%) assigned to usual care, a difference driven by differential use of high-flow nasal cannula (74.7% vs. 2.8%). A total of 57 patients (15.9%) in the protocolized support group experienced reintubation compared with 52 patients (13.3%) in the usual care group (odds ratio, 1.23; 95% confidence interval, 0.82 to 1.84; P = 0.32).Conclusions: Among a broad population of critically ill adults undergoing extubation from invasive mechanical ventilation at an academic medical center, protocolized postextubation respiratory support, primarily characterized by an increase in the use of high-flow nasal cannula, did not prevent reintubation compared with usual care.Clinical trial registered with www.clinicaltrials.gov (NCT0328831).

Longitudinal associations of parental monitoring and delinquent peer affiliation: The potential influence of parental solicitation and monitoring rules.

INTRODUCTION: Poor parental monitoring has been theorized as a key risk factor for an adolescent's association with deviant peers. However, measurements of parental monitoring often only measure parental knowledge rather than parental monitoring actions, leaving the true longitudinal associations between parental monitoring and peer delinquency unclear. METHODS: The current sample consisted of 1095 male justice-involved adolescents (13-17 years old at baseline collected between 2011 and 2013) from across the United States who provided survey data every 6 months for 3 years. Longitudinal associations between parental monitoring constructs (i.e., parental solicitation and monitoring rules) and peer delinquency were tested using random intercept cross-lagged panel models to investigate both between-individual associations and within-individual bidirectional effects. RESULTS: Although parental monitoring and peer delinquency were negatively related at a between-individual level, very few within-individual directional effects were found. The few within-individual effects present indicated that parental solicitation predicted greater peer delinquency and peer delinquency predicted fewer parental monitoring rules over time. CONCLUSIONS: Current findings indicate that, while greater overall parental monitoring is associated with less peer delinquency, there is little evidence that changes in parental monitoring lead to reductions in peer delinquency over time. Results support previous findings suggesting parental monitoring should not be the sole target of intervention for reducing peer delinquency.

Embryonic stem cell-derived exosomes promote endogenous repair mechanisms and enhance cardiac function following myocardial infarction.

RATIONALE: Embryonic stem cells (ESCs) hold great promise for cardiac regeneration but are susceptible to various concerns. Recently, salutary effects of stem cells have been connected to exosome secretion. ESCs have the ability to produce exosomes, however, their effect in the context of the heart is unknown. OBJECTIVE: Determine the effect of ESC-derived exosome for the repair of ischemic myocardium and whether c-kit(+) cardiac progenitor cells (CPCs) function can be enhanced with ESC exosomes. METHODS AND RESULTS: This study demonstrates that mouse ESC-derived exosomes (mES Ex) possess ability to augment function in infarcted hearts. mES Ex enhanced neovascularization, cardiomyocyte survival, and reduced fibrosis post infarction consistent with resurgence of cardiac proliferative response. Importantly, mES Ex augmented CPC survival, proliferation, and cardiac commitment concurrent with increased c-kit(+) CPCs in vivo 8 weeks after in vivo transfer along with formation of bonafide new cardiomyocytes in the ischemic heart. miRNA array revealed significant enrichment of miR290-295 cluster and particularly miR-294 in ESC exosomes. The underlying basis for the beneficial effect of mES Ex was tied to delivery of ESC specific miR-294 to CPCs promoting increased survival, cell cycle progression, and proliferation. CONCLUSIONS: mES Ex provide a novel cell-free system that uses the immense regenerative power of ES cells while avoiding the risks associated with direct ES or ES-derived cell transplantation and risk of teratomas. ESC exosomes possess cardiac regeneration ability and modulate both cardiomyocyte and CPC-based repair programs in the heart.

Enhanced potency of cell-based therapy for ischemic tissue repair using an injectable bioactive epitope presenting nanofiber support matrix.

The translation of cell-based therapies for ischemic tissue repair remains limited by several factors, including poor cell survival and limited target site retention. Advances in nanotechnology enable the development of specifically designed delivery matrices to address these limitations and thereby improve the efficacy of cell-based therapies. Given the relevance of integrin signaling for cellular homeostasis, we developed an injectable, bioactive peptide-based nanofiber matrix that presents an integrin-binding epitope derived from fibronectin, and evaluated its feasibility as a supportive artificial matrix for bone marrow-derived pro-angiogenic cells (BMPACs) used as a therapy in ischemic tissue repair. Incubation of BMPACs with these peptide nanofibers in vitro significantly attenuated apoptosis while enhancing proliferation and adhesion. Pro-angiogenic function was enhanced, as cells readily formed tubes. These effects were, in part, mediated via p38, and p44/p42 MAP kinases, which are downstream pathways of focal adhesion kinase. In a murine model of hind limb ischemia, an intramuscular injection of BMPACs within this bioactive peptide nanofiber matrix resulted in greater retention of cells, enhanced capillary density, increased limb perfusion, reduced necrosis/amputation, and preserved function of the ischemic limb compared to treatment with cells alone. This self-assembling, bioactive peptide nanofiber matrix presenting an integrin-binding domain of fibronectin improves regenerative efficacy of cell-based strategies in ischemic tissue by enhancing cell survival, retention, and reparative functions.

The Mood Disorder Assessment Schedule: Initial validation of a new measure for early identification of bipolar spectrum disorders in inpatient adolescents.

Due to the significant impairment associated with subthreshold bipolar symptomatology and the harmful effects of delayed diagnosis, there is a great need for diagnostic tools that can facilitate early identification of bipolar spectrum disorders. The Mood Disorder Assessment Schedule (MDAS) is a newly developed measure that focuses on autonomous changes in mood and energy, a key indicator of bipolar spectrum problems which is not included in current diagnostic tools for bipolar disorders. The current study tested the ability of the MDAS to identify individuals at risk for bipolar spectrum disorders. In a cross-sectional sample of 396 inpatient adolescents, the MDAS identified a group of individuals with several bipolar spectrum disorder (BSD) indicators, including greater manic and depressive symptoms, affective lability, suicidal behavior, adverse reactions to antidepressants, and a family history of bipolar disorder and suicidal behavior. When compared to a standard diagnostic interview for bipolar disorders (i.e., Kiddie Schedule for Affective Disorders and Schizophrenia [KSADS]), the MDAS yielded stronger clinical utility in its ability to identify individuals with BSD indicators. Therefore, the MDAS appears to be a promising diagnostic tool for identifying adolescents at risk for BSDs and may help facilitate earlier diagnosis and prevent harmful effects of improper treatment.

The bidirectional effects of antisocial behavior, anxiety, and trauma exposure: Implications for our understanding of the development of callous-unemotional traits.

The association of anxiety and trauma with antisocial behavior in children and adolescents has long been the focus of research, and more recently this area of research has become critical to theories of the development of callous-unemotional (CU) traits. Research suggests those with elevated CU traits and anxiety (i.e., secondary CU variant) seem to show more severe externalizing behaviors and are more likely to show histories of trauma, compared to those with elevated CU and low anxiety (i.e., primary CU variant). These findings have typically been interpreted as being indicative of distinct etiological pathways to the development of CU traits. We test an alternative explanation that the higher rates of anxiety and trauma exposure in some youth with elevated CU traits are largely a consequence of their higher levels of antisocial behavior. The current study recruited a sample of 1,216 justice-involved adolescents (Mage = 15.28, SD = 1.28) from three distinct regions of the United States, who were assessed at 6, 12, 18, 24, 30, 36, 48, and 60 months following their first arrest. Using random-intercept cross-lagged models, both antisocial behavior and CU traits predicted changes in future anxiety and CU traits predicted increases in future victimization. Further, using longitudinal parallel mediation models, antisocial and aggressive behavior largely accounted for the predictive association between CU traits and anxiety and CU traits and victimization. These results support a model in which anxiety and trauma histories may be a marker of the severity of antisocial behavior displayed by youth with elevated CU traits. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The Brief Adolescent Depression Screen: A Brief Screening Tool for Depression and Suicidal Behavior in Inpatient Adolescents.

Background: In clinical settings, there is significant need for brief, easily-administered assessment tools for adolescent depression that can be used by mental health clinicians from a variety of training backgrounds. Existing depression screening tools do not assess for duration and consistency of symptoms, two key indicators of pathological depression. Objective: The Brief Adolescent Depression Screen (BADS) was developed to screen for major and persistent depressive disorders in adolescents in order to meet the assessment needs in an inpatient setting, and the validity of this tool was tested. Method: The current study used a sample of 396 inpatient adolescents to assess the screening utility of the BADS for detecting whether the adolescent meets criteria for a depressive diagnosis according to a well-validated semi-structured interview, as well as detecting a positive history of suicidal behavior. Further, the screening utility of this measure was compared to the utility of an established depression rating scale. Results: Analyses first determined the duration of depressive symptoms on the BADS that optimally screened for the presence of Major Depressive Disorder and Persistent Depressive Disorder. Findings indicated that, using these optimal screening cut-offs, the BADS showed a strong screening utility, resulting in a sensitivity and specificity for identifying full depressive diagnoses and a positive history of suicidal behavior with similar or greater accuracy than an established rating scale. Conclusions: These findings provide initial evidence to suggest that the BADS may be a helpful screening tool for adolescent depressive disorders in inpatient settings.

The associations of maternal warmth and hostility with prosocial and antisocial outcomes in justice-involved adolescents.

Parental warmth and hostility are two key dimensions of parenting for child development, but the differential effects of these parenting dimensions on child prosocial and antisocial development has not been adequately investigated. The current study hypothesized that parental warmth would be uniquely related to child callous-unemotional traits and prosocial behavior, whereas parental hostility would be uniquely related to child delinquency and aggression. These hypotheses were investigated in a diverse sample of 1,216 adolescent males (13 to 17 years old, 46% Latino, 37% Black) with justice-system involvement in the 5 years following their first arrest. Hybrid models estimated within- and between-individual associations over time, while controlling for the overlap between parental warmth and hostility and between child prosocial and antisocial outcomes. Results indicated that maternal warmth showed consistent associations with callous-unemotional traits and prosocial behavior over time, whereas maternal hostility showed consistent associations with delinquency and aggression over time. Further, the findings were similar across racial and ethnic groups. Implications for developmental models of antisocial behavior, particularly for those including the role of callous-unemotional traits, are discussed. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Palliative Care for Patients on Extracorporeal Membrane Oxygenation for COVID-19 Infection.

BACKGROUND: Critically ill patients with COVID-19 infection on extracorporeal membrane oxygenation (ECMO) face high morbidity and mortality. Palliative care consultation may benefit these patients and their families. Prior to the pandemic, our institution implemented a policy of automatic palliative care consultation for all patients on ECMO due to the high mortality, medical complexity, and psychosocial distress associated with these cases. OBJECTIVES: The main objective was to describe the role of the palliative care team for patients on ECMO for COVID-19 infection. The secondary objective was to describe the clinical outcomes for this cohort. DESIGN: Case series. SETTINGS/SUBJECTS: All patients age 18 or older infected by the novel coronavirus who required cannulation on ECMO from March through July of 2020, at an urban, academic medical center in the United States. Inter-disciplinary palliative care consultation occurred for all patients. RESULTS: Twenty-three patients (median age 43 years [range 28-64], mean body mass index 34.9 kg/m2 [SD 9.2], 65% Hispanic ethnicity) were cannulated on ECMO. Eleven patients died during the hospitalization (48%). Patients older than 50 years of age demonstrated a trend toward increased odds of death compared to those younger than 50 years of age (OR 9.1, P = 0.07). Patients received an average of 6.8 (SD 3.7) palliative clinical encounters across all disciplines. The actions provided by the palliative care team included psychosocial support and counseling, determination of surrogate decision maker (for 100% of patients), pain management (83%), and non-pain symptom management (83%). CONCLUSIONS: Here, we present one of the first studies describing the patient characteristics, outcomes, and palliative care actions for critically ill patients with COVID-19 on ECMO. Almost half of the patients in this cohort died during their hospitalization. Given the high morbidity and mortality of this condition, we recommend involvement of palliative care for patients/families with COVID-19 infection who are on ECMO. The impact of palliative care on patient and family outcomes, such as symptom control, satisfaction with communication, rates of anxiety, and grief experience merits further investigation.

Minimal change disease in a patient receiving checkpoint inhibition: Another possible manifestation of kidney autoimmunity?

BACKGROUND: Nivolumab has been associated with immune-related adverse events, including nephritis, with acute interstitial nephritis being the most commonly reported renal manifestation. CASE: We describe the first case to our knowledge of minimal change disease with nephrotic syndrome associated with the PD-1 checkpoint inhibitor, Nivolumab. Minimal change disease has been reported with other immune checkpoint inhibitors; however, this is the first reported case with Nivolumab. We report development of nephrotic syndrome with acute kidney injury in a 57-year-old man, 1 month after commencement of Nivolumab for metastatic squamous cell carcinoma of the tongue. Minimal change disease was confirmed by renal biopsy. Management with corticosteroids and cessation of Nivolumab failed to improve kidney function or nephrosis. CONCLUSION: This case adds to current literature identifying minimal change as an additional complication of immune checkpoint inhibitor-associated acute kidney injury. Given the increasing use of immune checkpoint inhibitors for a range of malignancies, nephrologists, oncologist and generalists should be aware of the spectrum of kidney pathologies associated with their use.

Microtubule acetylation through HDAC6 inhibition results in increased transfection efficiency.

The success of viral and nonviral gene delivery relies on the ability of DNA-based vectors to traverse the cytoplasm and reach the nucleus. We, as well as other researchers, have shown that plasmids utilize the microtubule network and its associated motor proteins to traffic toward the nucleus. While disruption of microtubules with nocodazole was shown to greatly inhibit cytoplasmic plasmid trafficking, it did not abolish it. It has been demonstrated that a pool of stabilized post-translationally acetylated microtubules exists in cells, and that this acetylation may play a role in protein trafficking. In order to determine whether this modification could account for the residual DNA trafficking in nocodazole-treated cells, we inhibited or knocked down the levels of the tubulin deacetylase, histone deacetylase 6 (HDAC6), thereby generating higher levels of acetylated microtubules. Electroporation of plasmids into cells with inhibited or silenced HDAC6 resulted in increased gene transfer. This increased transfection efficiency was not because of increased transcriptional activity, but rather, because of increased cytoplasmic trafficking. When plasmids were cytoplasmically microinjected into HDAC6-deficient cells, they entered the nucleus within 5 minutes of injection, almost 10 times faster than in wild-type cells. Taken together, these results suggest that modulation of HDAC6 and the microtubule network can increase the efficiency of gene transfer.

Protocolized Post-Extubation Respiratory Support to prevent reintubation: protocol and statistical analysis plan for a clinical trial.

INTRODUCTION: Following extubation from invasive mechanical ventilation, nearly one in seven critically ill adults requires reintubation. Reintubation is independently associated with increased mortality. Postextubation respiratory support (non-invasive ventilation or high-flow nasal cannula applied at the time of extubation) has been reported in small-to-moderate-sized trials to reduce reintubation rates among hypercapnic patients, high-risk patients without hypercapnia and low-risk patients without hypercapnia. It is unknown whether protocolised provision of postextubation respiratory support to every patient undergoing extubation would reduce the overall reintubation rate, compared with usual care. METHODS AND ANALYSIS: The Protocolized Post-Extubation Respiratory Support (PROPER) trial is a pragmatic, cluster cross-over trial being conducted between 1 October 2017 and 31 March 2019 in the medical intensive care unit of Vanderbilt University Medical Center. PROPER compares usual care versus protocolized post-extubation respiratory support (a respiratory therapist-driven protocol that advises the provision of non-invasive ventilation or high-flow nasal cannula based on patient characteristics). For the duration of the trial, the unit is divided into two clusters. One cluster receives protocolised support and the other receives usual care. Each cluster crosses over between treatment group assignments every 3 months. All adults undergoing extubation from invasive mechanical ventilation are enrolled except those who received less than 12 hours of mechanical ventilation, have 'Do Not Intubate' orders, or have been previously reintubated during the hospitalisation. The anticipated enrolment is approximately 630 patients. The primary outcome is reintubation within 96 hours of extubation. ETHICS AND DISSEMINATION: The trial was approved by the Vanderbilt Institutional Review Board. The results will be submitted for publication in a peer-reviewed journal and presented at one or more scientific conferences. TRIAL REGISTRATION NUMBER: NCT03288311.

Intracellular trafficking of plasmids for gene therapy: mechanisms of cytoplasmic movement and nuclear import.

Under physiologically relevant conditions, the levels of non-viral gene transfer are low at best. The reason for this is that many barriers exist for the efficient transfer of genes to cells, even before any gene expression can occur. While many transfection strategies focus on DNA condensation and overcoming the plasma membrane, events associated with the intracellular trafficking of the DNA complexes have not been as extensively studied. Once internalized, plasmids must travel potentially long distances through the cytoplasm to reach their next barrier, the nuclear envelope. This review summarizes the current progress on the cytoplasmic trafficking and nuclear transport of plasmids used for gene therapy applications. Both of these processes utilize specific and defined mechanisms to facilitate movement of DNA complexes through the cell. The continued elucidation and exploitation of these mechanisms will lead to improved strategies for transfection and successful gene therapy.

Growth differentiation factor-5 enhances in vitro mesenchymal stromal cell chondrogenesis and hypertrophy.

The regenerative potential for adult bone marrow-derived mesenchymal stromal cells (MSCs) has been extensively investigated in the setting of arthritic disease and focal cartilage defects. In vitro chondrogenic differentiation of MSCs is regularly accomplished by the widely used pellet culture system where MSCs are maintained in high-density pellets to mimic mesenchymal condensation during development. Supplementation of chondrogenic MSC pellet cultures with growth differentiation factor-5 (GDF-5), a highly regulated gene in the chondrogenic phase of endochondral ossification (EO), was investigated here under the hypothesis that GDF-5 will enhance the chondrogenic differentiation of MSCs, thereby supporting their entry into ossification. The supplementation of chondrogenic MSC pellets with the recombinant human GDF-5 protein significantly enhanced MSC chondrogenic differentiation, as demonstrated by enhanced collagen type II and sulfated glycosaminoglycan (GAG) incorporation into the extracellular matrix. Increased P-SMADs 1-5-8 were observed in pellets treated with GDF-5 and transforming growth factor (TGF)-ß 3 when compared to the pellets treated with TGF-ß 3 alone, demonstrated by immunostaining and western blot analysis of the chondrogenic pellet extract. A concurrent increase in alkaline phosphatase, collagen types I and X, and osteopontin secretion indicated a transition of these cultures to hypertrophy. Together, these data support the application of GDF-5 to enhance MSC chondrogenic differentiation and hypertrophy as a precursor to EO.