The Fang laboratory has broad interests and deep expertise in vascular biology, non-coding genome, and nano-medicine. We investigate the pathophysiological mechanisms of vascular diseases, particularly the modulation of vascular health by non-coding genome in the context of cardiovascular complication (atherosclerosis) and pulmonary disease (acute lung injury). Our major research goals are 1) to elucidate novel non-coding genome-mediated disease mechanisms and 2) to develop new nanomedicine-based diagnostic and therapeutic applications
Non-coding genome related to vascular diseases:
Non-coding DNA contributes to ~98% of human genome and intergenic/intronic sequences have emerged as critical regulatory elements in providing evolutionary complexity. The roles of non-coding DNA are poorly understood overall, and they have only recently been explored with respect to mediating vascular functions related to cardiovascular and pulmonary diseases. Employing multi-disciplinary approaches including high-throughput sequencing, bioinformatics, human genetics, bioengineering systems, cell/molecular biology techniques as well as experimental in vivo and in vitro models, we have demonstrated that non-coding genomic sequences mediate the susceptibility to atherosclerosis by participating in mechano-transduction mechanisms in two ways. First, non-coding small RNAs in endothelia are tightly regulated by blood flow characteristics in vitro and in vivo and mechano-sensitive miRNAs causatively determine the endothelial phenotypes in relation to athero-susceptibility. Specifically, athero-susceptible disturbed flow inhibits miR-10a and activates miR-92a leading to NFkB activation and inhibition of Kruppel-like factor 2 (KLF2) and Kruppel-like factor 4 (KLF4), two anti-inflammatory transcription factors. Second, non-coding DNA engages in the mechano-transduction mechanisms by regulating critical flow-sensitive genes in endothelial cells. Specifically, athero-protective flow mediates the anti-inflammatory endothelial phenotype by stimulating PhosPhatidic-Acid-Phosphatase-type-2B (PPAP2B) that harbors an intronic single nucleotide polymorphism (SNP) associated with coronary artery disease identified by genome-wide association studies (GWAS).
Mechano-biology in vascular diseases:
Organisms from bacteria to eukaryotes have evolved specific molecular mechanisms to respond to the physical three-dimensional environment. Cells convert mechanical forces and deformations into electrochemical activity through mechano-transduction mechanisms. Mechano-biology modulates key cellular behaviors such as lineage specification, differentiation, proliferation, migration, and apoptosis. Dys-regulation of mechano-transduction mechanisms contributes to a wide range of human complications, such as cardiovascular diseases, inflammatory lungs diseases, fibrotic diseases, and cancers. For instance, atherosclerotic disease, the leading cause of human morbidity and mortality, principally develops at sites where vascular endothelial cells are activated by local disturbed blood flow. Moreover, mechanical ventilation that aims to accelerate the gas exchange in critically ill patients has been linked to regional lung over-distention, leading to increased circumferential stretch of pulmonary micro-vasculatures and consequent lung injury (Ventilator-Induced Lung Injury/VILI). Our major research goals are to 1) elucidate novel mechano-transduction mechanisms related to atherosclerosis and VILI, and 2) develop new microRNA-based diagnostic and therapeutic applications.
Nanomedicine in vascular diseases:
Dysfunctional endothelium contributes to more human disorders than any other tissue. Delivery of therapeutic nucleotides to dysfunctional endothelial cells has the potential to treat various vascular diseases such as atherosclerosis and acute lung injury. However, efficient delivery of therapeutic nucleotides to endothelial cells in vivo has so far been problematic and remains challenging. Moreover, the non-specific targeting of therapeutic nucleotides via systemic delivery has remained an issue that can cause unwanted side effects. In collaboration with Dr. Matthew Tirrell (Institute for Molecular Engineering, U of Chicago), we have recently engineered novel “targeted” polyelectrolyte complex micelles that effectively deliver functional miRNA inhibitors to dysfunctional vascular endothelial cells. Specifically, cationic cores, which effectively carry negatively-charged nucleotides, were engineered in self-assembled ~20 nM nanoparticles that were “functionalized” to bind selectively to single or multiple proteins/receptors by attaching targeting peptides to the micelle surface. Notably, the modularity of this platform and high surface area:volume ratio of nanoparticles allows us to engineer micelles with dual/multiple display of peptides targeting various types of cells where distinct targetable membrane receptors are expressed. Various therapeutic nucleotides, such as miRNA inhibitors/mimics, small interfering RNAs, and transcripts can be selectively encapsulated for accommodating a wide range of therapeutic strategies.