Harnessing developmental cues for cardiomyocyte production.

Developmental research has attempted to untangle the exact signals that control heart growth and size, with knockout studies in mice identifying pivotal roles for Wnt and Hippo signaling during embryonic and fetal heart growth. Despite this improved understanding, no clinically relevant therapies are yet available to compensate for the loss of functional adult myocardium and the absence of mature cardiomyocyte renewal that underlies cardiomyopathies of multiple origins. It remains of great interest to understand which mechanisms are responsible for the decline in proliferation in adult hearts and to elucidate new strategies for the stimulation of cardiac regeneration. Multiple signaling pathways have been identified that regulate the proliferation of cardiomyocytes in the embryonic heart and appear to be upregulated in postnatal injured hearts. In this Review, we highlight the interaction of signaling pathways in heart development and discuss how this knowledge has been translated into current technologies for cardiomyocyte production.

pH-Responsive doxorubicin delivery using shear-thinning biomaterials for localized melanoma treatment.

Injectable shear-thinning biomaterials (STBs) have attracted significant attention because of their efficient and localized delivery of cells as well as various molecules ranging from growth factors to drugs. Recently, electrostatic interaction-based STBs, including gelatin/LAPONITE® nanocomposites, have been developed through a simple assembly process and show outstanding shear-thinning properties and injectability. However, the ability of different compositions of gelatin and LAPONITE® to modulate doxorubicin (DOX) delivery at different pH values to enhance the effectiveness of topical skin cancer treatment is still unclear. Here, we fabricated injectable STBs using gelatin and LAPONITE® to investigate the influence of LAPONITE®/gelatin ratio on mechanical characteristics, capacity for DOX release in response to different pH values, and cytotoxicity toward malignant melanoma. The release profile analysis of various compositions of DOX-loaded STBs under different pH conditions revealed that lower amounts of LAPONITE® (6NC25) led to higher pH-responsiveness capable of achieving a localized, controlled, and sustained release of DOX in an acidic tumor microenvironment. Moreover, we showed that 6NC25 had a lower storage modulus and required lower injection forces compared to those with higher LAPONITE® ratios. Furthermore, DOX delivery analysis in vitro and in vivo demonstrated that DOX-loaded 6NC25 could efficiently target subcutaneous malignant tumors via DOX-induced cell death and growth restriction.

Elevated Plasma Immunoglobulin Levels Prior to Heart Transplantation Are Associated with Poor Post-Transplantation Survival.

Cardiac allograft vasculopathy (CAV) and antibody-mediated rejection are immune-mediated, long-term complications that jeopardize graft survival after heart transplantation (HTx). Interestingly, increased plasma levels of immunoglobulins have been found in end-stage heart failure (HF) patients prior to HTx. In this study, we aimed to determine whether increased circulating immunoglobulin levels prior to transplantation are associated with poor post-HTx survival. Pre-and post-HTx plasma samples of 36 cardiac transplant recipient patients were used to determine circulating immunoglobulin levels. In addition, epicardial tissue was collected to determine immunoglobulin deposition in cardiac tissue and assess signs and severity of graft rejection. High levels of IgG1 and IgG2 prior to HTx were associated with a shorter survival post-HTx. Immunoglobulin deposition in cardiac tissue was significantly elevated in patients with a survival of less than 3 years. Patients with high plasma IgG levels pre-HTx also had significantly higher plasma levels after HTx. Furthermore, high pre-HTX levels of IgG1 and IgG2 levels were also significantly increased in patients with inflammatory infiltrate in CAV lesions. Altogether the results of this proof-of-concept study suggest that an activated immune response prior to transplantation negatively affects graft survival.

Thrombolytic Agents: Nanocarriers in Controlled Release.

Thrombosis is a life-threatening pathological condition in which blood clots form in blood vessels, obstructing or interfering with blood flow. Thrombolytic agents (TAs) are enzymes that can catalyze the conversion of plasminogen to plasmin to dissolve blood clots. The plasmin formed by TAs breaks down fibrin clots into soluble fibrin that finally dissolves thrombi. Several TAs have been developed to treat various thromboembolic diseases, such as pulmonary embolisms, acute myocardial infarction, deep vein thrombosis, and extensive coronary emboli. However, systemic TA administration can trigger non-specific activation that can increase the incidence of bleeding. Moreover, protein-based TAs are rapidly inactivated upon injection resulting in the need for large doses. To overcome these limitations, various types of nanocarriers have been introduced that enhance the pharmacokinetic effects by protecting the TA from the biological environment and targeting the release into coagulation. The nanocarriers show increasing half-life, reducing side effects, and improving overall TA efficacy. In this work, the recent advances in various types of TAs and nanocarriers are thoroughly reviewed. Various types of nanocarriers, including lipid-based, polymer-based, and metal-based nanoparticles are described, for the targeted delivery of TAs. This work also provides insights into issues related to the future of TA development and successful clinical translation.

Synthesis of Injectable Shear-Thinning Biomaterials of Various Compositions of Gelatin and Synthetic Silicate Nanoplatelet.

Injectable shear-thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varying compositions of gelatin and SNPs to navigate their material, mechanical, rheological, and bioactive properties. All compositions (each component percentage; 1.5-4.5%/total solid ranges; 3-9%) tested are injectable through both 5 Fr general catheter and 2.4 Fr microcatheter by manual pressure. In the results, an increase in gelatin contents causes decrease in swellability, increase in freeze-dried hydrogel scaffold porosity, increase in degradability and injection force during iSTB fabrication. Meanwhile, the amount of SNPs in composite hydrogels is mainly required to decrease degradability and increase shear thinning properties of iSTB. Finally, in vitro and in vivo biocompatibility tests show that the 1.5-4.5% range gelatin-SNP iSTBs are not toxic to the cells and animals. All results demonstrate that the iSTB can be modulated with specific properties for unmet clinical needs. Understanding of mechanical and biological consequences of the changing gelatin-SNP ratios through this study will shed light on the biomedical applications of iSTB on specific diseases.

In Vitro Human Liver Model of Nonalcoholic Steatohepatitis by Coculturing Hepatocytes, Endothelial Cells, and Kupffer Cells.

The liver has a complex and unique microenvironment with multiple cell-cell interactions and internal vascular networks. Although nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease with multiple phases, no proper model could fully recapitulate the in vivo microenvironment to understand NAFLD progression. Here, an in vitro human liver model of NAFLD by coculturing human hepatocytes, umbilical vein endothelial cells (HUVECs), and Kupffer cells (KCs) into spheroids is presented. Analysis of indirect cross-talk using conditioned media between steatotic spheroids-composed of hepatocellular carcinoma-derived cells (HepG2) and HUVECs-and mouse KCs reveals that the latter can be activated showing increased cell area, elevated production of reactive oxygen species (ROS), and proinflammatory cytokines. Spheroids incorporating human KCs (HKCs) can also be induced into steatotic stage by supplementing fat. Steatotic spheroids with/without HKCs show different levels of steatotic stages through lipid accumulation and ROS production. Steatotic spheroids made from an immortalized hepatic progenitor cell line (HepaRG) compared to those made from HepG2 cells display similar trends of functionality, but elevated levels of proinflammatory cytokines, and improved reversibility of steatosis. The in vitro human liver system proposed makes strides in developing a model to mimic and monitor the progression of NAFLD.