Khawaja Husnain Haider

Sonic Hedgehog Gene Delivery to the Rodent Heart Promotes Angiogenesis via iNOS/Netrin-1/PKC Pathway

Background We hypothesized that genetic modification of mesenchymal stem cells (MSCs) with Sonic Hedgehog (Shh) transgene, a morphogen during embryonic development and embryonic and adult stem cell growth, improved their survival and angiogenic potential in the ischemic heart via iNOS/netrin/PKC pathway. Methods/Principal Findings MSCs from young Fisher-344 rat bone marrow were purified and transfected with pCMV Shh plasmid (ShhMSCs). Immunofluorescence, RT-PCR and Western blotting showed higher expression of Shh in ShhMSCs which also led to increased expression of angiogenic and pro-survival growth factors in ShhMSCs. Significantly improved migration and tube formation was seen in ShhMSCs as compared to empty vector transfected MSCs (EmpMSCs). Significant upregulation of netrin-1 and iNOS was observed in ShhMSCs in PI3K independent but PKC dependent manner. For in vivo studies, acute myocardial infarction model was developed in Fisher-344 rats. The animals were grouped to receive 70 µl basal DMEM without cells (group-1) or containing 1×106 EmpMSCs (group-2) and ShhMSCs (group-3). Group-4 received recombinant netrin-1 protein injection into the infarcted heart. FISH and sry-quantification revealed improved survival of ShhMSCs post engraftment. Histological studies combined with fluorescent microspheres showed increased density of functionally competent blood vessels in group-3 and group-4. Echocardiography showed significantly preserved heart function indices post engraftment with ShhMSCs in group-3 animals. Conclusions/Significance Reprogramming of stem cells with Shh maximizes their survival and angiogenic potential in the heart via iNOS/netrin-1/PKC signaling.

Identification and Characterization of a Novel Multipotent Sub-Population of Sca-1+ Cardiac Progenitor Cells for Myocardial Regeneration

Methods and Results The cardiac stem/progenitor cells from adult mice were seeded at low density in serum-free medium. The colonies thus obtained were expanded separately and assessed for expression of stem cell antigen-1 (Sca-1). Two colonies each with high Sca-1 (CSH1; 95.9%; CSH2; 90.6%) and low Sca-1 (CSL1; 37.1%; CSL2; 17.4%) expressing cells were selected for further studies. Sca-1+ cells (98.4%) isolated using Magnetic Cell Sorting System (MACS) from the hearts were used as a control. Although the selected populations were similar in surface marker expression (low in c-kit, CD45, CD34, CD31 and high in CD29), these cells exhibited diverse differentiation potential. Unlike CSH1, CSH2 expressed Nanog, TERT, Bcrp1, Nestin, Musashi1 and Isl-1, and also showed differentiation into osteogenic, chondrogenic, smooth muscle, endothelial and cardiac lineages. MACS sorted cells exhibited similar tendency albeit with relatively weaker differentiation potential. Transplantation of CSH2 cells into infarcted heart showed attenuated infarction size, significantly preserved left ventricular function and anterior wall thickness, and increased capillary density. We also observed direct differentiation of transplanted cells into endothelium and cardiomyocytes. Conclusions The cardiac stem/progenitor cells isolated by a combined clonal selection and surface marker approach possessed multiple stem cell features important for cardiac regeneration.

Skeletal myoblasts for cardiac repair

Stem cells provide an alternative curative intervention for the infarcted heart by compensating for the cardiomyocyte loss subsequent to myocardial injury. The presence of resident stem and progenitor cell populations in the heart, and nuclear reprogramming of somatic cells with genetic induction of pluripotency markers are the emerging new developments in stem cell-based regenerative medicine. However, until safety and feasibility of these cells are established by extensive experimentation in in vitro and in vivo experimental models, skeletal muscle-derived myoblasts, and bone marrow cells remain the most well-studied donor cell types for myocardial regeneration and repair. This article provides a critical review of skeletal myoblasts as donor cells for transplantation in the light of published experimental and clinical data, and indepth discussion of the advantages and disadvantages of skeletal myoblast-based therapeutic intervention for augmentation of myocardial function in the infarcted heart. Furthermore, strategies to overcome the problems of arrhythmogenicity and failure of the transplanted skeletal myoblasts to integrate with the host cardiomyocytes are discussed.

MicroRNA-143 is a critical regulator of cell cycle activity in stem cells with co-overexpression of Akt and angiopoietin-1 via transcriptional regulation of Erk5/cyclin D1 signaling

We report that simultaneous expression of Akt and angiopoietin-1 (Ang-1) transgenes supported mitogenesis in stem cells with a critical role for microRNA-143 (miR-143) downstream of FoxO1 transcription factor. Mesenchymal stem cells (MSC) from young male rats were transduced with Ad-vectors encoding for Akt (AktMSC) and Ang-1 (Ang-1MSC) transgenes for their individual or simultaneous overexpression (AAMSC; > 5-fold gene level and > 4-fold Akt and Ang-1 protein expression in AAMSC vs. Ad-Empty transduced MSC; EmpMSC). AAMSC had higher phosphorylation of FoxO1, which activated Erk5, a distinct mitogen-induced MAPK that drove transcriptional activation of cyclin D1 and Cdk4. Flow cytometry showed > 10% higher S-phase cell population that was confirmed by BrdU assay (15%) and immunohistology for Ki67 (11%) in AAMSC using EmpMSC as controls. miR array supported by real-time PCR showed induction of miR-143 in AAMSC (4.73-fold vs.. EmpMSC). Luciferase assay indicated a dependent relationship between miR-143 and Erk5 in AAMSC. FoxO1-specific siRNA upregulated miR-143, whereas inhibition of miR-143 did not change FoxO1 activation. However, miR-143 inhibition repressed phosphorylation of Erk5 and abrogated cyclin D1 with concomitant reduction in cells entering cell cycle. During in vivo studies, male GFP+ AAMSC transplanted into wild-type female infarcted rat hearts showed significantly higher number of Ki67 expressing cells (p < 0.05 vs. EmpMSC) 7 days after engraftment (n = 4 animals/group). In conclusion, co-overexpression of Akt and Ang-1 in MSC activated cell cycle progression by upregulation of miR-143 and stimulation of FoxO1 and Erk5 signaling.

Stem cell-based delivery of Hypoxamir-210 to the infarcted heart: implications on stem cell survival and preservation of infarcted heart function.

This study seeks to test our hypothesis that transgenic induction of miR-210 in mesenchymal stem cells (MSC) simulates the pro-survival effects of ischemic preconditioning (IPC) and that engraftment of PCMSC helps in the functional recovery of ischemic heart by miR-210 transfer to host cardiomyocytes through gap junctions. miR-210 expression in MSC was achieved by IPC or nanoparticle-based transfection of miR-210 plasmid (miRMSC) and functional recovery of the infarcted heart of rat transplanted with PCMSC or miRMSC was evaluated. Both PCMSC and miRMSC showed higher survival under lethal anoxia as compared to non-PCMSC and scramble-transfected MSC (ScMSC) controls with concomitantly lower CASP8AP2 expression. Similarly, both PCMSC and miRMSC survived better and accelerated functional recovery of ischemic heart post-transplantation. To validate our hypothesis that MSC deliver miR-210 to host cardiomyocytes, in vitro co-culture between cardiomyocytes and PCMSC or miRMSC (using non-PCMSC or ScMSC as controls) showed co-localization of miR-210 with gap-junctional connexin-43. miR-210 transfer to cardiomyocytes was blocked by heptanol pretreatment. Moreover, higher survival of cardiomyocytes co-cultured with PCMSC was observed with concomitant expression of CASP8AP2 as compared to cardiomyocytes co-cultured with non-PCMSC thus suggesting that miR-210 was translocated from MSC to protect host cardiomyocytes. Induction of miR-210 in MSC promoted their survival post-engraftment in the infarcted heart. Moreover, direct transfer of pro-survival miR-210 from miRMSC to host cardiomyocytes led to functional recovery of the ischemic heart.

Concomitant activation of miR-107/PDCD10 and hypoxamir-210/Casp8ap2 and their role in cytoprotection during ischemic preconditioning of stem cells.

AIMS To establish a functional link between microRNA-107 (miR-107) and stem cell survival during ischemic preconditioning (IPC) of stem cells with multiple cycles of brief anoxia/re-oxygenation (10 or 30 min, one to three cycles) and show that the cytoprotective effects were independent of hypoxamir-210. RESULTS We demonstrated the induction of miR-107 in response to the IPC-induced activation of Akt/hypoxia inducible factor-1α (HIF-1α) in preconditioned mesenchymal stem cells ((PC)MSC), which showed improved survival during subsequent exposure to 6 h of lethal anoxia (p<0.05 vs. non-preconditioned MSC[(non-PC)MSC]). In silico analysis and luciferase activity assay confirmed programmed cell death-10 (PDCD10) as a putative target of miR-107 in (PC)MSC, which was significantly reduced during IPC and inversely related to stem cell survival under 6 h of lethal anoxia. Loss-of-function studies with miR-107 antagomir showed a significantly reduced survival of (PC)MSC. A comparison of miR-107 and miR-210 showed that both miRs participated independently via their respective putative target genes Pdcd10 and Casp8ap2. The simultaneous abrogation of Pdcd10 and Casp8ap2 had a stronger effect on (PC)MSC survival under lethal anoxia. The transplantation of (PC)MSC in an acute model of myocardial infarction showed a significantly improved survival of transplanted (PC)MSC with concomitantly enhanced miR-107 expression in (PC)MSC-transplanted animal hearts. INNOVATION Cytoprotection afforded by IPC is regulated by miR-107 induction via Pdcd10 independent of miR-210/Casp8ap2 signaling, and the simultaneous abrogation miR-107/miR-210 has a stronger effect on the loss of (PC)MSC survival. CONCLUSION IPC enhances stem cell survival via the combined participation of hypoxia responsive miRs miR-107 and miR-210 via their respective putative target genes Pdcd10 and Casp8ap2.

Activation of diverse signaling pathways by Ex-vivo delivery of multiple cytokines for myocardial repair

We tested the hypothesis that simultaneous transgenic overexpression of a select quartet of growth factors activates diverse signaling pathways for mobilization and participation of various stem/progenitor cells for cardiogenesis in the infarcted heart. Human insulin growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 (SDF-1a), and hepatocyte growth factor (HGF) plasmids were synthesized and transfected into skeletal myoblasts (SM) from young male wild-type or transgenic rats expressing green fluorescent protein (GFP). Overexpression of growth factors in transfected SM ((Trans)SM) was confirmed by reverse transcription polymerase chain reaction, western blotting, and fluorescence immunostaining. Using our custom-made growth factor array and western blotting, multiple angiogenic and prosurvival factors were detected in (Trans)SM, including secreted frizzled related protein-1,2,4,5, matrix metalloproteinases-3 and 9, connexin-43, netrin-1, Nos-2, Wnt-3, Akt, MAPK42/44, Stat3, nuclear factor kappa B (NFκB), hypoxia-inducible factor 1 (HIF-1α), and protein kinase C (PKC). The conditioned medium (CM) from (Trans)SM was cytoprotective for cardiomyocytes following H(2)O(2) treatment [P<0.01 vs. CM from native SM ((Nat)SM)], promoted a higher transwell migration of human umbilical cord vein endothelial cells (223.3±1.8, P<0.01) and in vitro tube formation (47.8±1.9, P<0.01). Intramyocardial transplantation of 1.5×10(6) (Trans)SM (group-3) in a rat model of acute myocardial infarction induced extensive mobilization of cMet(+), ckit(+), ckit(+)/GATA(4+), CXCR4(+), CD44(+), CD31(+), and CD59(+) cells into the infarcted heart on day 7 and improved integration of (Trans)SM in the heart compared to (Nat)SM (group 2) (P<0.05). Extensive neomyogenesis and angiogenesis in group-3 (P<0.01 vs. group-2), with resultant attenuation of infarct size (P<0.01 vs. group-2) and improvement in global heart function (P<0.01 vs. group-2) was observed at 8 weeks. In conclusion, simultaneous activation of diverse signaling pathways by overexpression of multiple growth factors caused massive mobilization and homing of stem/progenitor cells from peripheral circulation, the bone marrow, and the heart for accelerated repair of the infarcted myocardium.

Subcellular preconditioning of stem cells: mito-Cx43 gene targeting is cytoprotective via shift of mitochondrial Bak and Bcl-xL balance

AIM To achieve mitochondria-specific expression of connexin-43 (Cx43) transgene for mitochondrial preconditioning in stem cells to improve their survival post-transplantation during heart cell therapy. METHODS & RESULTS Cx43- or GFP-encoding adenoviral vectors with a mitochondrial targeting sequence were constructed for transduction of bone marrow Sca-1(+) cells (>90% transduction efficiency). Double-fluorescence immunostaining for cytochrome-c and Cx43 supported by western blotting confirmed mitochondria-specific Cx43 expression in adenoviral-mito-Cx43-transduced cells ((Cx43)Sca-1(+)). (Cx43)Sca-1(+) showed improved survival under lethal oxygen-glucose deprivation culture conditions. (Cx43)Sca-1(+) showed an increased mitochondrial Bcl-xL:Bak ratio and reduced cytochrome-c release into cytosol with concomitantly abolished caspase-3 activity. An in vivo study was performed such that 2 × 10(6) male (Cx43)Sca-1(+) or (GFP)Sca-1(+) cells were injected into a female rat model of acute myocardial infarction. DMEM-injected rats served as controls. On day 7 post-transplantation, 4.3-fold higher survival of (Cx43)Sca-1(+) cells (p < 0.05 vs control) and reduced terminal deoxynucleotidyl transferase dUTP nick end labeling positivity in the left ventricle (LV) were observed. In comparison, LV ejection fraction (40.2 ± 0.9%), LV fractional shortening (20.0 ± 1.6%) and LV end diastolic dimension (6.5 ± 0.3 mm) were observed in (GFP)Sca-1(+), and treatment with (Cx43)Sca-1(+) cells improved these parameters (47.6 ± 2.5%, p < 0.05; 27.7 ± 1.2%, p < 0.05; and 5.6 ± 0.1 mm, p < 0.05, respectively), along with concomitant reductions in infarction size (33.7 ± 2.9% vs 39.8 ± 1.4%; p < 0.05). CONCLUSION Mitochondria-targeted Cx43 expression is a novel approach to improve stem cell survival in the infarcted heart.

Insulin-Like Growth Factor-1 Preconditioning Accentuates Intrinsic Survival Mechanism in Stem Cells to Resist Ischemic Injury by Orchestrating Protein Kinase Cα–Erk1/2 Activation

AIMS To test our hypothesis that the intrinsic molecular mechanism in stem cells for adaptation to ischemia is accentuated by preconditioning with insulin-like growth factor (IGF-1). RESULTS Bone marrow Sca-1(+) cells were exposed to oxygen and glucose deprivation (OGD) for up to 12 h. Erk1/2 was activated in Sca-1(+) cells under OGD which was blocked by MEK inhibitor (PD98059) and resulted in accelerated cell death. Moreover, elevated intracellular calcium with concomitant activation of protein kinase C (PKC) was observed under OGD. Pretreatment with nifedipine or dantrolene reduced cellular calcium, abrogated PKC and Erk1/2 activation, and increased cytotoxicity. Treatment with phorbol 12-myristate 13-acetate (PMA) for 30 min (short-term) activated Erk1/2, whereas 12 h (long-term) PMA treatment abrogated PKCα, reduced Erk1/2 activation and significantly increased cell death under OGD. These results were confirmed by loss-of-function studies using PKCα and Erk1/2 specific small interfering RNA. Gain-of-function studies with PKCα plasmid transfection improved cell survival under OGD. Preconditioning with 100 nM IGF-1 accentuated the intrinsic mechanism of resistance of the cells to ischemia via Erk1/2 activation and improved their survival under OGD as well as post-transplantation in an experimentally infarcted heart. INNOVATION Strategies to target intrinsic survival mechanism in stem cells by growth factor preconditioning to enhance their survival via activation of PKCα and Erk1/2 are innovative. CONCLUSIONS Intracellular calcium elevation under OGD activated PKCα and Erk1/2 as a part of the intrinsic prosurvival mechanism that was accentuated during preconditioning with IGF-1 to protect Sca-1(+) cells from ischemic injury.

Cytoprotective and Proangiogenic Activity of Ex-Vivo Netrin-1 Transgene Overexpression Protects the Heart Against Ischemia/Reperfusion Injury

In continuation of a previous work that transgene expression of sonic hedgehog promoted neo-vascularization via netrin-1 release, the current study was aimed at assessing the anti-apoptotic and pro-angiogenic role of netrin-1 transgene overexpression in the ischemic myocardium. pLP-Adeno-X ViralTrak vectors containing netrin-1 cDNA amplified from rat mesenchymal stem cells (Ad-netrin) or without a therapeutic gene (Ad-null) were constructed and transfected into HEK-293 cells to produce Ad-netrin and Ad-null vectors. Sca-1(+)-like cells were isolated and propagated in vitro and were successfully transduced with Ad-netrin transduced Sca-1(+) cells ((Net)Sca-1(+)) and Ad-null transduced Sca-1(+) cells ((Null)Sca-1(+)). Overexpression of netrin-1 in (Net)Sca-1(+) was confirmed by reverse transcription-polymerase chain reaction and western blot. Neonatal cardiomyocytes and rat endothelial cells expressed netrin-1 specific receptor Uncoordinated-5b and the conditioned medium from (Net)Sca-1(+) cells was protective for both the cell types against oxidant stress. For in vivo studies, the rat model of myocardial ischemia/reperfusion injury was developed in female Wistar rats by left anterior descending coronary artery occlusion for 45 min followed by reperfusion. The animals were grouped to receive 70 μL of Dulbeccos modified Eagles medium without cells (group-1), containing 2×10(6) (Null)Sca-1(+) cells (group-2) and (Net)Sca-1(+) cells (group-3). (Net)Sca-1(+) cells significantly reduced ischemia/reperfusion injury in the heart and preserved the global heart function in group-3 (P<0.05 vs. groups-1 and group-2). Ex-vivo netrin-1 overexpression in the heart increased NOS activity in the heart. Blood vessel density was significantly higher in group-3 (P<0.05 vs. controls). We concluded that netrin-1 decreased apoptosis in cardiomyocytes and endothelial cells via activation of Akt. Netrin-1 transgene expression was proangiogenic and effectively reduced ischemia/reperfusion injury to preserve global heart function.