Bridging the Gap: Advances and Challenges in Heart Regeneration from In Vitro to In Vivo Applications.

Cardiovascular diseases, particularly ischemic heart disease, area leading cause of morbidity and mortality worldwide. Myocardial infarction (MI) results in extensive cardiomyocyte loss, inflammation, extracellular matrix (ECM) degradation, fibrosis, and ultimately, adverse ventricular remodeling associated with impaired heart function. While heart transplantation is the only definitive treatment for end-stage heart failure, donor organ scarcity necessitates the development of alternative therapies. In such cases, methods to promote endogenous tissue regeneration by stimulating growth factor secretion and vascular formation alone are insufficient. Techniques for the creation and transplantation of viable tissues are therefore highly sought after. Approaches to cardiac regeneration range from stem cell injections to epicardial patches and interposition grafts. While numerous preclinical trials have demonstrated the positive effects of tissue transplantation on vasculogenesis and functional recovery, long-term graft survival in large animal models is rare. Adequate vascularization is essential for the survival of transplanted tissues, yet pre-formed microvasculature often fails to achieve sufficient engraftment. Recent studies report success in enhancing cell survival rates in vitro via tissue perfusion. However, the transition of these techniques to in vivo models remains challenging, especially in large animals. This review aims to highlight the evolution of cardiac patch and stem cell therapies for the treatment of cardiovascular disease, identify discrepancies between in vitro and in vivo studies, and discuss critical factors for establishing effective myocardial tissue regeneration in vivo.

Dynamic Narrowing of the Diaphragmatic Vena Cava in Ovis aries.

Dorset sheep (Ovis aries) are common models in translational cardiovascular research due to physiologic and anatomic similarities to humans. While employing ovine subjects to study single-ventricle physiology, we repeatedly observed position-based changes in central venous pressure (CVP) which could not be explained by hydrostatic (gravitational) effects. Inferior vena cava (IVC) narrowing or compression has been demonstrated in numerous species, and we hypothesised that this phenomenon might explain our observations in O. aries. This study aimed to characterise position-dependent morphology of the IVC in O. aries using catheter-based hemodynamic and dimensional measurements, three-dimensional MRI reconstruction and histological analysis. Baseline measurements revealed a significant reduction in IVC dimensions at the level of the diaphragm (dVC) compared to the abdominal vena cava (aVC) and thoracic vena cava (tVC). We also observed a transdiaphragmatic pressure gradient along the IVC, with higher pressures in the aVC compared to the tVC. We found that variation of position and fluid status altered IVC haemodynamics. Histological data showed variable muscularity along the length of the IVC, with greater smooth muscle content in the aVC than the tVC. These findings will improve understanding of baseline ovine physiology, help refine experimental protocols and facilitate the translation of findings to the clinic.

Robotic Beating-Heart Totally Endoscopic Coronary Artery Bypass: Impact of Chest Wall Dimensions in Single and Multivessel Bypass.

OBJECTIVE: There can be anatomical constraints on patient selection for minimally invasive surgery. For example, robot-assisted coronary artery bypass was reported to be more challenging when patients had a cardiothoracic ratio >50% and a sternum-vertebra anteroposterior and transverse diameter ratio <0.45. We sought to examine the impact of chest wall anatomic parameters on surgical outcomes in our totally endoscopic coronary artery bypass (TECAB) procedures. METHODS: We retrospectively reviewed patients who underwent robotic TECAB, all of whom had a preoperative chest radiograph at our institution from July 2017 to October 2021. The cohort was divided into 2 groups, which were patients undergoing single-vessel grafting using the left internal thoracic artery (ITA; group 1) and patients undergoing multivessel grafting with bilateral ITA grafts (group 2). We measured several anatomical parameters from the preoperative chest radiograph. RESULTS: A total of 352 patients undergoing TECAB were retrospectively analyzed. After exclusions, 193 were included in this study. In group 1 (n = 91), no parameters correlated with operative time. In group 2 (n = 102), a significant negative correlation was observed between operative time and the sternum-vertebrae anteroposterior diameter (rs = -0.228, P = 0.022) and lung anteroposterior diameter (rs = -0.246, P = 0.013). To confirm these results in group 2, a propensity-matched analysis was performed and showed a statistically significant difference in surgical time based on chest anteroposterior diameters. CONCLUSIONS: In single-vessel robotic TECAB, chest wall anatomic dimensions measured on chest radiograph did not affect operative time. In multivessel cases with bilateral ITA grafts, larger anteroposterior diameter correlated with shorter operative times.

Quantifying Inferior Vena Cava Compliance and Distensibility in an In Vivo Ovine Model Using 3D Angiography.

Synthetic vascular grafts overcome some challenges of allografts, autografts, and xenografts but are often more rigid and less compliant than the native vessel into which they are implanted. Compliance matching with the native vessel is emerging as a key property for graft success. The current gold standard for assessing vessel compliance involves the vessel's excision and ex vivo biaxial mechanical testing. We developed an in vivo method to assess venous compliance and distensibility that better reflects natural physiology and takes into consideration the impact of a pressure change caused by flowing blood and by any morphologic changes present. This method is designed as a survival procedure, facilitating longitudinal studies while potentially reducing the need for animal use. Our method involves injecting a 20 mL/kg saline bolus into the venous vasculature, followed by the acquisition of pre and post bolus 3D angiograms to observe alterations induced by the bolus, concurrently with intravascular pressure measurements in target regions. We are then able to measure the circumference and the cross-sectional area of the vessel pre and post bolus. With these data and the intravascular pressure, we are able to calculate the compliance and distensibility with specific equations. This method was used to compare the inferior vena cava's compliance and distensibility in native unoperated sheep to the conduit of sheep implanted with a long-term expanded polytetrafluorethylene (PTFE) graft. The native vessel was found to be more compliant and distensible than the PTFE graft at all measured locations. We conclude that this method safely provides in vivo measurements of vein compliance and distensibility.

Patient-specific tissue engineered vascular graft for aortic arch reconstruction.

Objectives: The complexity of aortic arch reconstruction due to diverse 3-dimensional geometrical abnormalities is a major challenge. This study introduces 3-dimensional printed tissue-engineered vascular grafts, which can fit patient-specific dimensions, optimize hemodynamics, exhibit antithrombotic and anti-infective properties, and accommodate growth. Methods: We procured cardiac magnetic resonance imaging with 4-dimensional flow for native porcine anatomy (n = 10), from which we designed tissue-engineered vascular grafts for the distal aortic arch, 4 weeks before surgery. An optimal shape of the curved vascular graft was designed using computer-aided design informed by computational fluid dynamics analysis. Grafts were manufactured and implanted into the distal aortic arch of porcine models, and postoperative cardiac magnetic resonance imaging data were collected. Pre- and postimplant hemodynamic data and histology were analyzed. Results: Postoperative magnetic resonance imaging of all pigs with 1:1 ratio of polycaprolactone and poly-L-lactide-co-ε-caprolactone demonstrated no specific dilatation or stenosis of the graft, revealing a positive growth trend in the graft area from the day after surgery to 3 months later, with maintaining a similar shape. The peak wall shear stress of the polycaprolactone/poly-L-lactide-co-ε-caprolactone graft portion did not change significantly between the day after surgery and 3 months later. Immunohistochemistry showed endothelization and smooth muscle layer formation without calcification of the polycaprolactone/poly-L-lactide-co-ε-caprolactone graft. Conclusions: Our patient-specific polycaprolactone/poly-L-lactide-co-ε-caprolactone tissue-engineered vascular grafts demonstrated optimal anatomical fit maintaining ideal hemodynamics and neotissue formation in a porcine model. This study provides a proof of concept of patient-specific tissue-engineered vascular grafts for aortic arch reconstruction.

Tissue engineered vascular grafts are resistant to the formation of dystrophic calcification.

Advancements in congenital heart surgery have heightened the importance of durable biomaterials for adult survivors. Dystrophic calcification poses a significant risk to the long-term viability of prosthetic biomaterials in these procedures. Herein, we describe the natural history of calcification in the most frequently used vascular conduits, expanded polytetrafluoroethylene grafts. Through a retrospective clinical study and an ovine model, we compare the degree of calcification between tissue-engineered vascular grafts and polytetrafluoroethylene grafts. Results indicate superior durability in tissue-engineered vascular grafts, displaying reduced late-term calcification in both clinical studies (p < 0.001) and animal models (p < 0.0001). Further assessments of graft compliance reveal that tissue-engineered vascular grafts maintain greater compliance (p < 0.0001) and distensibility (p < 0.001) than polytetrafluoroethylene grafts. These properties improve graft hemodynamic performance, as validated through computational fluid dynamics simulations. We demonstrate the promise of tissue engineered vascular grafts, remaining compliant and distensible while resisting long-term calcification, to enhance the long-term success of congenital heart surgeries.

In Situ Myocardial Regeneration With Tissue Engineered Cardiac Patch Using Spheroid-Based 3-Dimensional Tissue.

BACKGROUND: We have developed a tissue engineered cardiac patch derived from a 3-dimensional (3D) myocardial tissue reinforced with extracellular matrix in an effort to enhance in situ myocardial regeneration. The feasibility of the patch was evaluated in a porcine model by various modalities to assess both the constructive and functional aspects of regeneration. METHODS: A spheroid-based 3D multicellular tissue was created using a 3D net mold system that incorporated cardiomyocytes and embryonic fibroblast cells. The 3D multicellular tissue was incorporated with extracellular matrix sheets and surgically implanted into the right ventricle of a healthy porcine model (n = 4). After 60 days, the implanted patches were evaluated by cardiac magnetic resonance imaging and electroanatomic mapping studies as well as by post-euthanasia analyses, including measurements of mechanical viscoelasticity. RESULTS: Cardiac magnetic resonance imaging revealed improved regional tissue perfusion in the patch area. Electroanatomic mapping exhibited regenerated electrical conductivity in the patch, as evidenced by relatively preserved voltage regions (1.11 ± 0.8 mV) in comparison to the normal right ventricle (4.7 ± 2.8 mV). Histologic and tissue analyses confirmed repopulation of site-specific host cells, including premature cardiomyocytes and active vasculogenesis. These findings were supported by quantitative reverse transcription-polymerase chain reaction. CONCLUSIONS: The tissue engineered cardiac patch effectively facilitated in situ constructive and functional myocardial regeneration, characterized by increased regional tissue perfusion and positive electrical activity in the porcine model.

Development of deep-learning models for real-time anaerobic threshold and peak VO2 prediction during cardiopulmonary exercise testing.

AIMS: Exercise intolerance is a clinical feature of patients with heart failure (HF). Cardiopulmonary exercise testing (CPET) is the first-line examination for assessing exercise capacity in patients with HF. However, the need for extensive experience in assessing anaerobic threshold (AT) and the potential risk associated with the excessive exercise load when measuring peak oxygen uptake (peak VO2) limit the utility of CPET. This study aimed to use deep-learning approaches to identify AT in real time during testing (defined as real-time AT) and to predict peak VO2 at real-time AT. METHODS AND RESULTS: This study included the time-series data of CPET recorded at the Department of Cardiovascular Medicine, Kyushu University Hospital. Two deep neural network models were developed to: (i) estimate the AT probability using breath-by-breath data and (ii) predict peak VO2 using the data at the real-time AT. The eligible CPET contained 1472 records of 1053 participants aged 18-90 years and 20% were used for model evaluation. The developed model identified real-time AT with 0.82 for correlation coefficient (Corr) and 1.20 mL/kg/min for mean absolute error (MAE), and the corresponding AT time with 0.86 for Corr and 0.66 min for MAE. The peak VO2 prediction model achieved 0.87 for Corr and 2.25 mL/kg/min for MAE. CONCLUSION: Deep-learning models for real-time CPET analysis can accurately identify AT and predict peak VO2. The developed models can be a competent assistant system to assess a patient's condition in real time, expanding CPET utility.

Cardiopulmonary exercise testing can be used to evaluate the condition of patients with heart failure during exercise. Developed deep-learning models can accurately predict a patient's anaerobic threshold in real time and peak oxygen uptake. The models can be used by clinicians for more objective and accurate assessments in real time, expanding the utility of cardiopulmonary exercise testing.

Umbilical Cord Blood Transplantation for Myelodysplastic Syndromes with Donor-Specific Anti-HLA Antibodies against HLA-DP.

The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) against anti-HLA-A, -B, -C, and -DRB1 in HLA-mismatched hematopoietic stem cell transplantation (HSCT) is associated with graft failure. DSAs against HLA-A, -B, -C, and -DRB1 with a mean fluorescence intensity (MFI) of greater than > 1,000 was shown to increase the risk of graft failure in single-unit umbilical cord blood transplantation (UCBT). Nevertheless, the impact of DSAs against HLA-DP or -DQ on transplantation outcomes is not fully understood. In this report, we present a case of UCBT in a patient with myelodysplastic syndrome who was positive for DSAs against HLA-DP with MFI of 1,263 before UCBT but successfully achieved neutrophil engraftment. If HLA-DP or -DQ is mismatched in UCBT, evaluating DSAs against HLA-DP or -DQ is crucial to avoid graft failure. However, the criteria for DSAs against HLA-A, -B, -C, and -DRB1 may not be directly applicable to those against HLA-DP or -DQ.

Sternal-Sparing Surgical Options in Combined Aortic Valve and Coronary Artery Disease: Proof of Concept.

OBJECTIVE: The standard management of concomitant aortic valve (AV) and coronary artery disease has been coronary artery bypass and AV replacement (AVR). With the advent of minimally invasive options, many isolated lesions have been successfully managed using a sternal-sparing approach. In our institution, patients with isolated AV disease are offered minimally invasive surgical or transcatheter AVR, and those with isolated coronary artery disease are routinely managed with robotic totally endoscopic coronary artery bypass or percutaneous coronary intervention. Various combinations of these techniques can be used when a sternal-sparing posture is desired because of patient risk or preference. The aim of this study was to review the outcomes in patients with combined AV and coronary disease who were managed using sternal-sparing approaches. METHODS: We reviewed the records of 10 patients in our minimally invasive surgical database who presented with concomitant AV and coronary artery disease and underwent combined sternal-sparing management of these 2 lesions using various combinations of minimally invasive approaches. RESULTS: Four patients had totally endoscopic coronary artery bypass and minimally invasive AVR at the same time, 2 patients underwent transcatheter AVR followed by totally endoscopic coronary artery bypass, and 4 patients underwent minimally invasive AVR with percutaneous coronary intervention. There was no 30-day mortality. The duration of postoperative surgical hospital stay was 3.1 ± 0.9 days. CONCLUSIONS: Sternal-sparing approaches in combined AV and coronary artery disease are feasible with patient-specific treatment selection of minimally invasive techniques.

Recent Tissue Engineering Approaches to Mimicking the Extracellular Matrix Structure for Skin Regeneration.

Inducing tissue regeneration in many skin defects, such as large traumatic wounds, burns, other physicochemical wounds, bedsores, and chronic diabetic ulcers, has become an important clinical issue in recent years. Cultured cell sheets and scaffolds containing growth factors are already in use but have yet to restore normal skin tissue structure and function. Many tissue engineering materials that focus on the regeneration process of living tissues have been developed for the more versatile and rapid initiation of treatment. Since the discovery that cells recognize the chemical-physical properties of their surrounding environment, there has been a great deal of work on mimicking the composition of the extracellular matrix (ECM) and its three-dimensional network structure. Approaches have used ECM constituent proteins as well as morphological processing methods, such as fiber sheets, sponges, and meshes. This review summarizes material design strategies in tissue engineering fields, ranging from the morphology of existing dressings and ECM structures to cellular-level microstructure mimicry, and explores directions for future approaches to precision skin tissue regeneration.

The Application of Porous Scaffolds for Cardiovascular Tissues.

As the number of arteriosclerotic diseases continues to increase, much improvement is still needed with treatments for cardiovascular diseases. This is mainly due to the limitations of currently existing treatment options, including the limited number of donor organs available or the long-term durability of the artificial organs. Therefore, tissue engineering has attracted significant attention as a tissue regeneration therapy in this area. Porous scaffolds are one of the effective methods for tissue engineering. However, it could be better, and its effectiveness varies depending on the tissue application. This paper will address the challenges presented by various materials and their combinations. We will also describe some of the latest methods for tissue engineering.

Recent Developments in Biopolymer-Based Hydrogels for Tissue Engineering Applications.

Hydrogels are being investigated for their application in inducing the regeneration of various tissues, and suitable conditions for each tissue are becoming more apparent. Conditions such as the mechanical properties, degradation period, degradation mechanism, and cell affinity can be tailored by changing the molecular structure, especially in the case of polymers. Furthermore, many high-functional hydrogels with drug delivery systems (DDSs), in which drugs or bioactive substances are contained in controlled hydrogels, have been reported. This review focuses on the molecular design and function of biopolymer-based hydrogels and introduces recent developments in functional hydrogels for clinical applications.

Advances in Cardiac Tissue Engineering.

Tissue engineering has paved the way for the development of artificial human cardiac muscle patches (hCMPs) and cardiac tissue analogs, especially for treating Myocardial infarction (MI), often by increasing its regenerative abilities. Low engraftment rates, insufficient clinical application scalability, and the creation of a functional vascular system remain obstacles to hCMP implementation in clinical settings. This paper will address some of these challenges, present a broad variety of heart cell types and sources that can be applied to hCMP biomanufacturing, and describe some new innovative methods for engineering such treatments. It is also important to note the injection/transplantation of cells in cardiac tissue engineering.

Trapping of CDC42 C-terminal variants in the Golgi drives pyrin inflammasome hyperactivation.

Mutations in the C-terminal region of the CDC42 gene cause severe neonatal-onset autoinflammation. Effectiveness of IL-1ß-blocking therapy indicates that the pathology involves abnormal inflammasome activation; however, the mechanism underlying autoinflammation remains to be elucidated. Using induced-pluripotent stem cells established from patients carrying CDC42R186C, we found that patient-derived cells secreted larger amounts of IL-1ß in response to pyrin-activating stimuli. Aberrant palmitoylation and localization of CDC42R186C protein to the Golgi apparatus promoted pyrin inflammasome assembly downstream of pyrin dephosphorylation. Aberrant subcellular localization was the common pathological feature shared by CDC42 C-terminal variants with inflammatory phenotypes, including CDC42*192C*24 that also localizes to the Golgi apparatus. Furthermore, the level of pyrin inflammasome overactivation paralleled that of mutant protein accumulation in the Golgi apparatus, but not that of the mutant GTPase activity. These results reveal an unexpected association between CDC42 subcellular localization and pyrin inflammasome activation that could pave the way for elucidating the mechanism of pyrin inflammasome formation.

Pharmacokinetics, Safety, and Tolerability of NPC-21, an Anti-Cytomegalovirus Monoclonal Antibody, in Healthy Japanese and White Adult Men: A Randomized, Placebo-Controlled, First-in-Human Phase 1 Study.

NPC-21 (EV2038) is a fully human monoclonal antibody that targets the antigenic domain 1 of glycoprotein B on the human cytomegalovirus (hCMV) envelope. NPC-21 has been shown to have broadly neutralizing activity and to inhibit cell-to-cell transmission of hCMV in preclinical studies. It is currently in development for the prophylactic or preemptive treatment of hCMV in patients receiving a solid-organ transplant or hematopoietic stem cell transplant. A first-in-human phase 1 study was conducted to assess the pharmacokinetics, safety, and tolerability of NPC-21 in healthy adult men. Forty participants (Japanese, n = 32; White, n = 8) were randomly assigned to receive a single intravenous dose of NPC-21 1, 3, 10, or 20 mg/kg or placebo. Six Japanese participants were included in each dose group and six White participants received a 10-mg/kg dose. The placebo group included 8 Japanese participants and 2 White participants. All 40 participants completed the study. Serum concentration, maximum serum concentration, area under the plasma concentration-time curve from time 0 to the last measurable concentration, and area under the plasma concentration-time curve from time 0 to infinity increased dose dependently; dose proportionality was linear. NPC-21 demonstrated a biphasic elimination pattern, with an estimated half-life between 612 and 790 hours. NPC-21 was safe and well tolerated up to 20 mg/kg. All adverse events were mild, and none led to treatment discontinuation or were considered related to the study drug. There were no differences in pharmacokinetics or safety between Japanese and White participants. These results support further investigation of NPC-21.

Clinical and Bacteriologic Characteristics of Six Cases of Bifidobacterium breve Bacteremia Due to Probiotic Administration in the Neonatal Intensive Care Unit.

BACKGROUND: Bifidobacterium breve is widely used as a probiotic in preterm infants and children with congenital surgical conditions, however, some cases of probiotics-induced bacteremia have been reported recently. OBJECTIVES: To examine the clinical and bacteriologic features of Bifidobacterium breve bacteremia caused by a probiotic (BBG-01) in term and preterm infants. METHODS: We included 298 patients who were admitted to the neonatal intensive care unit of Miyagi Children's Hospital and were given BBG-01 as a probiotic within the period June 2014 to February 2019. We experienced six cases of B. breve bacteremia and assessed their features retrospectively. RESULTS: The incidence rate of B. breve bacteremia in our hospital was 2% (6/298), higher than reported previously. The median age at onset, corrected age, and weight of the patients was 8 days (range: 5-27 days), 35 weeks (range: 26-39 weeks), and 1,940 g (range: 369-2734 g), respectively. The bacteremia triggers were gastrointestinal perforations in two cases, food protein-induced enterocolitis syndrome in two cases, adhesive ileus in one case, ileal volvulus in one case, and aspiration pneumonia following esophageal atresia repair in one case. B. breve was detected on blood cultures after a median of 5 days 13 hours (range: 4 days 18 hours-9 days 13 hours). No patient demonstrated serious symptoms, such as septic shock. All patients received antibiotics and recovered without any sequelae. CONCLUSIONS: Ileus and intestinal mucosal damage, such as enteritis, can cause B. breve bacteremia. The incidence of B. breve bacteremia may be higher than reported previously and detection via culture may require a longer time than typically needed for more common bacteria. It is associated with a good prognosis.

How Community Pharmacists Perceive Ethics in Clinical Research: A Qualitative Study.

In recent years, the importance of building evidence in clinical practice that is increasingly acknowledged globally has been recognized in Japan as well, and it is expected that clinical research by community pharmacists will grow. In Japan, however, community pharmacists have few opportunities to learn about research ethics and may lack the training to make ethical decisions. We conducted a questionnaire survey of community pharmacists (n = 200) using a free descriptive format to understand how they perceived research ethics. Our qualitative analysis of 170 respondents revealed various perspectives (, , and ) of Japanese pharmacists on ethics in the context of clinical research. With respect to how to understand research, the following perspectives were found: "research that prioritizes researchers," "research that prioritizes research subjects (patients)," and "research that enters into regular work." The perspectives on "research that prioritizes research subjects (patients)" and "research that enters into regular work" may inadvertently lead to ethically inappropriate research due to mismatch in professional values or poor understanding of research. These findings can contribute to the development of an educational program for community pharmacists on research ethics.