Bioprocess development for cord blood mesenchymal stromal cells on microcarriers in Vertical-Wheel bioreactors.

Equine mesenchymal stromal cells (MSCs) have been found to be beneficial for the treatment of many ailments, including orthopedic injuries, due to their superior differentiation potential and immunomodulating properties. Cell therapies require large cell numbers, which are not efficiently generated using conventional static expansion methods. Expansion of equine cord blood-derived MSCs (eCB-MSCs) in bioreactors, using microcarriers as an attachment surface, has the potential to generate large numbers of cells with increased reproducibility and homogeneity compared with static T-flask expansion. This study investigated the development of an expansion process using Vertical-Wheel (VW) bioreactors, a single-use bioreactor technology that incorporates a wheel instead of an impeller. Initially, microcarriers were screened at small scale to assess eCB-MSC attachment and growth and then in bioreactors to assess cell expansion and harvesting. The effect of different donors, serial passaging, and batch versus fed batch were all examined in 0.1 L VW bioreactors. The use of VW bioreactors with an appropriate microcarrier was shown to be able to produce cell densities of up to 1E6 cells/mL, while maintaining cell phenotype and functionality, thus demonstrating great potential for the use of these bioreactors to produce large cell numbers for cell therapies.

Enhanced drug classification using machine learning with multiplexed cardiac contractility assays.

Cardiac screening of newly discovered drugs remains a longstanding challenge for the pharmaceutical industry. While therapeutic efficacy and cardiotoxicity are evaluated through preclinical biochemical and animal testing, 90 % of lead compounds fail to meet safety and efficacy benchmarks during human clinical trials. A preclinical model more representative of the human cardiac response is needed; heart tissue engineered from human pluripotent stem cell derived cardiomyocytes offers such a platform. In this study, three functionally distinct and independently validated engineered cardiac tissue assays are exposed to increasing concentrations of known compounds representing 5 classes of mechanistic action, creating a robust electrophysiology and contractility dataset. Combining results from six individual models, the resulting ensemble algorithm can classify the mechanistic action of unknown compounds with 86.2 % predictive accuracy. This outperforms single-assay models and offers a strategy to enhance future clinical trial success aligned with the recent FDA Modernization Act 2.0.

Challenges and opportunities in downstream separation processes for mesenchymal stromal cells cultured in microcarrier-based stirred suspension bioreactors.

Mesenchymal stromal cells (MSC) are a promising platform for regenerative medicine applications because of their multilineage differentiation abilities and ease of collection, isolation, and growth ex vivo. To meet the demand for clinical applications, large-scale manufacturing will be required using three-dimensional culture platforms in vessels such as stirred suspension bioreactors. As MSCs are an adherent cell type, microcarriers are added to the culture to increase the available surface area for attachment and growth. Although extensive research has been performed on efficiently culturing MSCs using microcarriers, challenges persist in downstream processing, including harvesting, filtration, and volume reduction, which all play a critical role in the translation of cell therapies to the clinic. The objective of this review is to assess the current state of downstream technologies available for microcarrier-based MSC cultures. This includes a review of current research within the three stages: harvesting, filtration, and volume reduction. Using this information, a downstream process for MSCs is proposed, which can be applied to a wide range of applications.

The Pathogenesis of Central and Complex Sleep Apnea.

PURPOSE: The purpose of this article is to review the recent literature on central apnea. Sleep disordered breathing (SDB) is characterized by apneas (cessation in breathing), and hypopneas (reductions in breathing), that occur during sleep. Central sleep apnea (CSA) is sleep disordered breathing in which there is an absence or diminution of respiratory effort during breathing disturbances while asleep. In obstructive sleep apnea (OSA), on the other hand, there is an absence of flow despite ongoing ventilatory effort. RECENT FINDINGS: Central sleep apnea is a heterogeneous disease with multiple clinical manifestations. OSA is by far the more common condition; however, CSA is highly prevalent among certain patient groups. Complex sleep apnea (CompSA) is defined as the occurrence/emergence of CSA upon treatment of OSA. Similarly, there is considerable overlap between CSA and OSA in pathogenesis as well as impacts. Thus, understanding sleep disordered breathing is important for many practicing clinicians.

Use of spironolactone to treat acne in adolescent females.

BACKGROUND/OBJECTIVES: Studies assessing the utility of spironolactone for treating acne in adolescent females are lacking. Thus, we sought to examine spironolactone's role in treating this patient population. METHODS: A retrospective review was performed to determine the efficacy of spironolactone treatment in adolescent females seen at Mayo Clinic in Rochester, Minnesota, from 2007 to 2017. RESULTS: In a cohort of 80 pediatric patients with a median age of 19 years (range, 14-20 years), 64 patients (80%) experienced improvement of acne on treatment with spironolactone (median dose, 100 mg daily) with a favorable side effect profile. Approximately a quarter of patients (22.5%) had a complete response; more than half (58.8%) had a complete response or a partial response greater than 50%. Initial and maximal responses were observed at a median of 3 months and 5 months, respectively. Patients received treatment with spironolactone for a median duration of 7 months (range, 3-45 months) with limited side effects. CONCLUSIONS: Spironolactone demonstrated efficacy in treating acne in adolescent females and is a safe long-term alternative to systemic antibiotics in these patients.

Reconstruction of cutaneous dorsal finger defects.

BACKGROUND: Reconstruction of surgical defects on the dorsal finger can be challenging because of a lack of adjacent tissue reservoirs, poor laxity, and often thin, atrophic skin surrounding the defect. OBJECTIVE: To present reconstructive options for cutaneous dorsal finger defects. METHODS: We describe our five preferred approaches to reconstructing cutaneous dorsal finger defects based on the amount of available underlying tissue and location of the defect on the finger. RESULTS: In the authors' opinion, for smaller defects between and including the metacarpophalangeal joint extending to the proximal interphalangeal joint, a transposition flap or unilateral advancement flap is preferable. For proximal finger defects that are wider, a unilateral rotation flap is appropriate. A Burow full-thickness skin graft can be used for any proximal defect with underlying soft tissue present. For defects with underlying bone or tendon present, a reverse cross-finger interpolation flap can be utilized. CONCLUSIONS: The unilateral advancement flap, unilateral rotation flap, transposition flap, full-thickness skin grafts, or the reverse cross-finger interpolation flap can be used to reconstruct the majority of cutaneous dorsal finger defects.

Large-scale expansion of feeder-free mouse embryonic stem cells serially passaged in stirred suspension bioreactors at low inoculation densities directly from cryopreservation.

Embryonic stem cells (ESCs) have almost unlimited proliferation capacity in vitro and can retain the ability to contribute to all cell lineages, making them an ideal platform material for cell-based therapies. ESCs are traditionally cultured in static flasks on a feeder layer of murine embryonic fibroblast cells. Although sufficient to generate cells for research purposes, this approach is impractical to achieve large quantities for clinical applications. In this study, we have developed protocols that address a variety of challenges that currently bottleneck clinical translation of ESCs expanded in stirred suspension bioreactors. We demonstrated that mouse ESCs (mESCs) cryopreserved in the absence of feeder cells could be thawed directly into stirred suspension bioreactors at extremely low inoculation densities (100 cells/ml). These cells sustained proliferative capacity through multiple passages and various reactor sizes and geometries, producing clinically relevant numbers (109 cells) and maintaining pluripotency phenotypic and functional properties. Passages were completed in stirred suspension bioreactors of increasing scale, under defined batch conditions which greatly improved resource efficiency. Output mESCs were analyzed for pluripotency marker expression (SSEA-1, SOX-2, and Nanog) through flow cytometry, and spontaneous differentiation and teratoma analysis was used to demonstrate functional maintenance of pluripotency.

Development of a bio-MEMS device for electrical and mechanical conditioning and characterization of cell sheets for myocardial repair.

Here we propose a bio-MEMS device designed to evaluate contractile force and conduction velocity of cell sheets in response to mechanical and electrical stimulation of the cell source as it grows to form a cellular sheet. Moreover, the design allows for the incorporation of patient-specific data and cell sources. An optimized device would allow cell sheets to be cultured, characterized, and conditioned to be compatible with a specific patient's cardiac environment in vitro, before implantation. This design draws upon existing methods in the literature but makes an important advance by combining the mechanical and electrical stimulation into a single system for optimized cell sheet growth. The device has been designed to achieve cellular alignment, electrical stimulation, mechanical stimulation, conduction velocity readout, contraction force readout, and eventually cell sheet release. The platform is a set of comb electrical contacts consisting of three-dimensional walls made of polydimethylsiloxane and coated with electrically conductive metals on the tops of the walls. Not only do the walls serve as a method for stimulating cells that are attached to the top, but their geometry is tailored such that they are flexible enough to be bent by the cells and used to measure force. The platform can be stretched via a linear actuator setup, allowing for simultaneous electrical and mechanical stimulation that can be derived from patient-specific clinical data.

Design Approaches to Myocardial and Vascular Tissue Engineering.

Engineered tissues represent an increasingly promising therapeutic approach for correcting structural defects and promoting tissue regeneration in cardiovascular diseases. One of the challenges associated with this approach has been the necessity for the replacement tissue to promote sufficient vascularization to maintain functionality after implantation. This review highlights a number of promising prevascularization design approaches for introducing vasculature into engineered tissues. Although we focus on encouraging blood vessel formation within myocardial implants, we also discuss techniques developed for other tissues that could eventually become relevant to engineered cardiac tissues. Because the ultimate solution to engineered tissue vascularization will require collaboration between wide-ranging disciplines such as developmental biology, tissue engineering, and computational modeling, we explore contributions from each field.

BSMV as a Biotemplate for Palladium Nanomaterial Synthesis.

The vast unexplored virus biodiversity makes the application of virus templates to nanomaterial synthesis especially promising. Here, a new biotemplate, Barley stripe mosaic virus (BSMV) was successfully used to synthesize organic-metal nanorods of similarly high quality to those produced with Tobacco mosaic virus (TMV). The mineralization behavior was characterized in terms of the reduction and adsorption of precursor and nanocrystal formation processes. The BSMV surface-mediated reduction of Pd(2+) proceeded via first-order kinetics in both Pd(2+) and BSMV. The adsorption equilibrium relationship of PdCl3H2O- on the BSMV surface was described by a multistep Langmuir isotherm suggesting alternative adsorbate-adsorbent interactions when compared to those on TMV. It was deduced that the first local isotherm is governed by electrostatically driven adsorption, which is then followed by sorption driven by covalent affinity of metal precursor molecules for amino acid residues. Furthermore, the total adsorption capacity of palladium species on BSMV is more than double of that on TMV. Finally, study of the BSMV-Pd particles by combining USAXS and SAXS enabled the characterization of all length scales in the synthesized nanomaterials. Results confirm the presence of core-shell cylindrical particles with 1-2 nm grains. The nanorods were uniform and monodisperse, with controllable diameters and therefore, of similar quality to those synthesized with TMV. Overall, BSMV has been confirmed as a viable alternate biotemplate with unique biomineralization behavior. With these results, the biotemplate toolbox has been expanded for the synthesis of new materials and comparative study of biomineralization processes.

High-titer manufacturing of SARS-CoV-2 Spike-pseudotyped VSV in stirred-tank bioreactors.

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic highlighted the importance of vaccine innovation in public health. Hundreds of vaccines built on numerous technology platforms have been rapidly developed against SARS-CoV-2 since 2020. Like all vaccine platforms, an important bottleneck to viral-vectored vaccine development is manufacturing. Here, we describe a scalable manufacturing protocol for replication-competent SARS-CoV-2 Spike-pseudotyped vesicular stomatitis virus (S-VSV)-vectored vaccines using Vero cells grown on microcarriers in a stirred-tank bioreactor. Using Cytodex 1 microcarriers over 6 days of fed-batch culture, Vero cells grew to a density of 3.95 ± 0.42 ×106 cells/mL in 1-L stirred-tank bioreactors. Ancestral strain S-VSV reached a peak titer of 2.05 ± 0.58 ×108 plaque-forming units (PFUs)/mL at 3 days postinfection. When compared to growth in plate-based cultures, this was a 29-fold increase in virus production, meaning a 1-L bioreactor produces the same amount of virus as 1,284 plates of 15 cm. In addition, the omicron BA.1 S-VSV reached a peak titer of 5.58 ± 0.35 × 106 PFU/mL. Quality control testing showed plate- and bioreactor-produced S-VSV had similar particle-to-PFU ratios and elicited comparable levels of neutralizing antibodies in immunized hamsters. This method should enhance preclinical and clinical development of pseudotyped VSV-vectored vaccines in future pandemics.

Bacterial-Nanocellulose-Based Biointerfaces and Biomimetic Constructs for Blood-Contacting Medical Applications.

Understanding the interaction between biomaterials and blood is critical in the design of novel biomaterials for use in biomedical applications. Depending on the application, biomaterials can be designed to promote hemostasis, slow or stop bleeding in an internal or external wound, or prevent thrombosis for use in permanent or temporary medical implants. Bacterial nanocellulose (BNC) is a natural, biocompatible biopolymer that has recently gained interest for its potential use in blood-contacting biomedical applications (e.g., artificial vascular grafts), due to its high porosity, shapeability, and tissue-like properties. To promote hemostasis, BNC has been modified through oxidation or functionalization with various peptides, proteins, polysaccharides, and minerals that interact with the coagulation cascade. For use as an artificial vascular graft or to promote vascularization, BNC has been extensively researched, with studies investigating different modification techniques to enhance endothelialization such as functionalizing with adhesion peptides or extracellular matrix (ECM) proteins as well as tuning the structural properties of BNC such as surface roughness, pore size, and fiber size. While BNC inherently exhibits comparable mechanical characteristics to endogenous blood vessels, these mechanical properties can be enhanced through chemical functionalization or through altering the fabrication method. In this review, we provide a comprehensive overview of the various modification techniques that have been implemented to enhance the suitability of BNC for blood-contacting biomedical applications and different testing techniques that can be applied to evaluate their performance. Initially, we focused on the modification techniques that have been applied to BNC for hemostatic applications. Subsequently, we outline the different methods used for the production of BNC-based artificial vascular grafts and to generate vasculature in tissue engineered constructs. This sequential organization enables a clear and concise discussion of the various modifications of BNC for different blood-contacting biomedical applications and highlights the diverse and versatile nature of BNC as a natural biomaterial.

The Impact of Underlying Obstructive Sleep Apnea Treatment on Exercise Capacity in Patients With Pulmonary Hypertension Undergoing a Cardiac Rehabilitation Program.

PURPOSE: Obstructive sleep apnea (OSA)-related pulmonary hypertension (PH) can often be reversed with treatment of OSA via continuous positive airway pressure. We hypothesized that treatment of OSA would be associated with a greater improvement in exercise capacity (EC) with cardiac rehabilitation (CR), especially in patients with PH as compared with those who are untreated. METHODS: We reviewed medical records of 315 consecutive patients who participated in CR. Pulmonary hypertension status was assessed on the basis of peak tricuspid regurgitant velocity (>2.8 m/sec) on pre-CR echocardiograms. The OSA status (no, untreated, or treated OSA) was determined on the basis of results from sleep studies, continuous positive airway pressure device data, and physician notes. Exercise capacity was assessed by measuring metabolic equivalents (METs) using a treadmill stress test before and after CR. RESULTS: We included 290 patients who participated in CR with available echocardiographic data: 44 (15%) had PH, and 102 (35%) had known OSA (30 treated and 72 untreated). Patients with OSA versus those with no OSA were more likely to have PH ( P = .06). Patients with PH versus no-PH were associated with significantly lower baseline METs in crude and adjusted analyses ( P ≤. 004). The PH and OSA status in isolation were not associated with changes in METs ( P > .2) with CR. There was a significant interaction between OSA treatment and PH in crude and adjusted analyses ( P ≤.01): treatment vs no treatment of OSA was associated with a clinically and statistically greater improvement in METs in patients who participated in CR with but not without PH. CONCLUSION: Baseline PH was associated with decreased baseline EC but did not attenuate CR-related improvements in METs. However, in the subset of OSA patients with PH, OSA therapy was associated with improved EC after CR.

Environmental Health Knowledge Does Not Necessarily Translate to Action in Youth.

Environmental challenges pose serious health problems, especially for children, and lay public action is lacking. This study sought to characterize the relationship between environmental health knowledge and behavior in youth. A cross-sectional, descriptive survey with quantitative and qualitative questions was conducted. Open-ended questions were coded to generate themes/subthemes. Subscales' scores were presented as mean ± SD or median and interquartile range (IQR). T- and Mann-Whitney tests were used to compare groups, and correlations were used to evaluate covariation. A total of 452 children were surveyed. Youth verbalized concerns about their environments and their impact on health. Air pollution was the most concerning issue. Participants had moderate knowledge scores. Few described the three health domains; even fewer included environment. Behavior scores were low and weakly correlated with knowledge, but were moderately correlated with attitude and self-efficacy. Participation in environmental classes, activities, and clubs was associated with higher scores. We found variable environmental health knowledge, limited understanding of the local environment's impact on health, and a weak association between youth's knowledge and behavior. Focused formal and non-formal educational experiences were associated with improved scores, indicating the value of targeted youth educational programming to increase environmental health knowledge and action.

Evaluation of an Infectious Diseases Elective for Early Clinical Medical Students on Their Internal Medicine Clerkship.

Background: Early medical subspecialty training is an emerging trend in medical education. These electives are still rare for Early Clinical Medical Students (ECMS). We describe the introduction of an Infectious Disease (ID) inpatient consult rotation elective for ECMS. Methods: In addition to seeing patients and rounding with the inpatient ID consult team, we created a supplemental curriculum to provide added support for ECMS that included a checklist of clinical skills learning objectives, self-directed, publicly available mini-lectures on ID topics, and an ID Coach who provided directed and personalized tutoring for students. We surveyed ECMS, ID fellows and attendings on service, and ID Coaches to evaluate the acceptability, feasibility, and effectiveness of this rotation and curriculum. Results: The majority of ECMS reported that the rotation was a useful educational experience and that the ID Coach was one of the most valuable aspects of the rotation. The majority of ID fellows and attendings reported that working with ECMS improved their job satisfaction and well-being. Conclusions: This multifaceted approach to early medical subspecialty training was valuable for ECMS, ID fellows, and faculty. Ongoing improvements in this curriculum will provide a useful tool for medical education.

Identification of sleep fragmentation-induced gut microbiota alteration and prediction of functional impact in Sprague Dawley rats harboring microbiome derived from multiple human donors.

Objectives: Poor quality sleep, including sleep fragmentation (SF), can result in severe health consequences. Gut microbiota symbiotically coexist with the host, making essential contributions to overall well-being. In this study, the effects of both acute (6-day) and chronic (6-week) SF in a humanized rat model were examined to evaluate the impact of SF on this symbiotic relationship. Material and Methods: Human fecal material was transplanted into antibiotic-treated, microbially depleted, Sprague Dawley rats. Animals were subjected to either acute or chronic SF and shifts to gut microbiota were investigated using 16S rRNA sequencing and predictive functional profiles were constructed with PICRUSt. We also investigated SF-induced intestinal microbial adhesion and penetration or increased microbial invasion of selected tissues and organs; as well as changes in crypt/villi architecture. Results: Microbiota profiling indicated that chronic, but not acute, SF significantly decreased the richness of alpha-diversity of distal ileum microbiota, and altered cecum and distal ileum beta-diversity; although both acute and chronic SF significantly changed select populations of microbiota in all three regions. Neither acute nor chronic SF induced changes to microbial adhesion, penetration, or invasion into intestinal tissues or nearby organs. Additionally, we found that chronic SF caused a reduction in villus height in the proximal colon. Discussion: Our study suggests that acute SF alters the gut microbiota in this humanized rat model, while chronic SF produces more pronounced changes to microbiota populations. This study identified potential microbiota targets for the prevention and/or intervention of the adverse effects of S F.