Alpha-calcitonin gene related peptide (α-CGRP) is a 37-amino acid cardioprotective neuropeptide. ... more Alpha-calcitonin gene related peptide (α-CGRP) is a 37-amino acid cardioprotective neuropeptide. Studies carried out in our laboratory and others establish α-CGRP as a potential therapeutic agent against a variety of cardiovascular diseases. However, the short half-life of α-CGRP limits its use in any long-term treatment regime. The goal of the present study is to develop an α-CGRP agonist analog with extended bioavailability using peptoid chemistry. A peptoid is a N -substituted glycine peptidomimetic molecule and is identical to α-amino acid except that the side chain in a peptoid is attached on the nitrogen rather than the α-carbon atom. Inclusion of a peptoid makes the native peptide protease-resistant and thus biostable in vivo . Using a solid-phase submonomer method, we synthesized a novel human α-CGRP analog containing two monomers of N -methoxyethylglycine (NMEG) peptoid at the N-terminus. Electrospray mass spectrometry (MALDI-TOF) analysis showed that the molecular mass of synthesized peptoid-peptide hybrid, NMEG-α-CGRP, was 4044 that is ~6.7% more than native peptide. An in vitro trypan blue cell exclusion assay demonstrated that incubation of NMEG-α-CGRP (5 μM) for 7 days did not affect the viability of rat H9C2 and mouse HL-1 cardiac cells. To evaluate the biological activity of NMEG-α-CGRP, a subcutaneous injection of human α-CGRP (10 μg/mice) and NMEG-α-CGRP (1, 3, 10, and 30 μg/mice) were given in 9-week-old C57BL6 mice (n=2 mice/dose), and blood pressure (BP) was measured using a tail-cuff method. A dose response curve showed that NMEG-α-CGRP decreased BP in mice in a time-dependent manner. Beginning with and injection of 3 μg of NMEG-α-CGRP, a dip in BP (85 ± 1 mmHg; in ±SD) was observed at 10 min after injection, and BP returned to baseline (125 mmHg) by 6 h, 18 h, and 24 h when injected with 3, 10, and 30 μg doses, respectively. Moreover, 10 μg of human-α-CGRP and NMEG-α-CGRP lowered BP from baseline for 2 h and 18 h, respectively, suggesting that NMEG addition increased stability, and thus bioavailability, of α-CGRP in vivo . In summary, our results show that a NMEG based α-CGRP modification is an effective approach to increase stability and, thus, bioavailability of α-CGRP in vivo making α-CGRP a viable therapeutic drug to treat cardiovascular diseases.
Purpose: Platelet-derived growth factor (PDGF) has previously been shown to influence lens growth... more Purpose: Platelet-derived growth factor (PDGF) has previously been shown to influence lens growth and transparency. The purpose of the present study was to investigate the expression of the PDGF receptor and its mRNA during lens development in chicken embryos. Methods: To examine the expression of PDGF receptor mRNAs, the authors used a combination of polymerase chain reaction, Northern blot analyses, and RNase protection assays. Platelet-derived growth factor receptors were studied using Western blot analyses and immunofluorescence-confocal microscopy. The mitogenic effects of PDGF were assayed using immunochemical detection of 5-bromo-2'-deoxyuridine incorporation into explanted lens epithelia. Results: The authors' studies strongly suggest that the PDGF alpha receptor is the only PDGF receptor present in the embryonic chicken lens during development because they were unable to detect the PDGF beta receptor using two different approaches. Northern blots showed that the chicken lens alpha receptor mRNA is similar in size to the mRNA encoding the human and frog alpha receptor, and Western blots detected a single band with a molecular weight of 170 kDa, close to the reported molecular weight for the human alpha receptor. After staining with specific antibodies, confocal microscopy localized the immunoreactivity to the membranes of the epithelial and annular pad cells. At early stages of development (E6), the PDGF alpha receptor was present throughout the epithelium. At later stages, immunoreactivity was restricted to the peripheral epithelium and the annular pad. The addition of human recombinant PDGF (AA or BB) to tissue cultured E6 chicken lens epithelia sustained cell proliferation significantly better than basal medium alone. Conclusions: The authors' studies provide the first evidence for PDGF alpha receptors in the chicken lens. Localization of these receptors to the peripheral lens epithelium during development and the mitogenic effect of exogenously added PDGF suggest a role for this growth factor in the control of lens growth.
The cardioprotective role of a neuropeptide, alpha-calcitonin gene related peptide (αCGRP), has b... more The cardioprotective role of a neuropeptide, alpha-calcitonin gene related peptide (αCGRP), has been established in a variety of cardiovascular diseases. To increase the bioavailability of the circulating peptide, we created a peptide delivery system by encapsulating αCGRP in an alginate biopolymer and showed that subcutaneous delivery of alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) on alternate days, up to 28 days, significantly protected hearts at pathophysiological levels in a transverse aortic constriction (TAC) pressure-overload induced heart failure murine model. The present study was performed to determine if weekly subcutaneous delivery of alginate-αCGRP microcapsules exhibited similar cardioprotective effects in TAC-mice as observed in our previous study with alternate days dose delivery scheme. This study is crucial to shed light on the efficacy of these microcapsules. An electrospray method was used to prepare alginate-αCGRP microcapsules of 200 μm diameter. Male C57BL6 mice were divided into four groups (3 mice/group): i- sham, ii- sham-alginate-CGRP, iii- TAC, and iv- TAC-alginate-CGRP. Mice from TAC and TAC-alginate-CGRP groups underwent TAC procedure. Two days post-TAC, alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) were administered subcutaneously once a week, up to 4 weeks, in the respective alginate-CGRP groups of mice. Short-axis echocardiography was performed to evaluate cardiac functions. After 28 days of microcapsules delivery, calculated percent fractional shortening (FS) and ejection fraction (EF) in mice were (in ±SD)- sham: FS= 47.6 ± 0.9, EF= 79.8 ± 0.9; sham-alginate-CGRP: FS= 47.3 ± 1.9, EF= 79.1 ± 2; TAC: FS= 34.1 ± 4.7, EF= 63.6 ± 7.1; TAC-alginate-CGRP: FS= 32.2 ± 2.3, EF= 61.0 ± 3.4. These echo data demonstrate that TAC heart failure mice had the usual significantly reduced cardiac functions, however weekly delivery of alginate-αCGRP microcapsules showed no improvement in heart performance in the TAC-mice. Combined results from our present and previous studies suggested that alginate-αCGRP microcapsules delivery on alternate days, but not weekly, is the most efficacious choice to achieve cardioprotective effects of αCGRP against pressure-induced heart failure in mice.
The embryonic lens contains two populations of cells, lens epithelial cells and lens fiber cells.... more The embryonic lens contains two populations of cells, lens epithelial cells and lens fiber cells. As the growth of the human lens is linear from the age of 10 to 90, lens epithelial cells divide and differentiate into fiber cells at a uniform rate during adulthood. Any defects that arise during fiber formation will remain in the lens. We postulate that regulation of early lens growth is critical for the onset of cataracts that usually occur later in life. Slowing the growth of the lens could therefore provide a strategy to suppress the formation of cataracts. However, the factor(s) that control lens growth in vivo have not been identified.We have identified 18 receptor and cytoplasmic kinases present in lens epithelial cells. Using these as potential targets for factors controlling growth, we tested corresponding ligands in a lens epithelial cell proliferation assay. Platelet-derived growth factor (PDGF) proved to promote a growth activity similar to, but distinct from, that of embryo serum.
Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indi... more Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
Introduction: Calcitonin gene-related peptide (CGRP), a 37 amino acid neuropeptide, is a potent v... more Introduction: Calcitonin gene-related peptide (CGRP), a 37 amino acid neuropeptide, is a potent vasodilator, and plays a critical role in the efferent functions of the sensory nervous system. A protective role for CGRP in cardiovascular diseases (hypertension, cardiac ischemia, and failure) has been well established by our laboratory and others. In the present study we determined whether long-term exogenous administration of α-CGRP protects against pressure-induced heart failure. Method: Three groups of nine-week-old C57/BL6 mice were studied: one group received a sham procedure (n= 4) and two groups underwent transverse aortic constriction (TAC). Two days after TAC, one group had CGRP-filled osmotic pumps (4 mg/kg bwt/day) implanted subcutaneously (n= 7) while the second group was TAC-only (n=6). At day 28, all groups had echocardiography performed and were sacrificed and heart tissue collected. Results: Echocardiographic and histological data showed that TAC markedly decreased fractional shortening (FS) and ejection fraction and increased heart and lung weight, cardiac hypertrophy, and fibrosis compared to sham. However, the TAC-CGRP mice had preserved cardiac function and less cardiac fibrosis (FS ±SEM: sham 46.2±1.8% vs TAC 25.4±1.1%, p < 0.001; and TAC 25.4±1.1% vs TAC-CGRP 36.6±1.2%, p < 0.001). CGRP significantly reduced apoptotic cell death and lipid peroxidation (an oxidative stress marker measured by malondialdehyde and 4-HNE staining) in the TAC hearts [malondialdehyde (nmol/mg protein) ±SEM: sham 3.5±0.19 vs TAC 14.3±0.57, p < 0.05; and TAC 14.3±0.57 vs TAC-CGRP 5.5±0.12, p < 0.05]. TAC alone decreased the level of p-ERK1/2 and increased p-JNK compared to sham. CGRP-TAC hearts had higher p-ERK1/2 levels but equal p-JNK levels compared to the TAC hearts. HIF1α and nrf2 protein levels were not different between experimental groups. Compared to TAC hearts, TAC-CGRP hearts had lower p-AMPK and nuclear Sirt1 level, regulatory proteins of energy metabolism. Conclusion: Our results suggest that CGRP, mediated through energy metabolic, and oxidative stress pathways, decreases myocyte apoptosis and is protective in pressure-induced heart failure. Thus, CGRP is a potential therapeutic agent in preventing the progression of heart failure.
The cardioprotective role of α-calcitonin gene related peptide (α-CGRP), a 37-amino acid neuropep... more The cardioprotective role of α-calcitonin gene related peptide (α-CGRP), a 37-amino acid neuropeptide and potent vasodilator, in cardiac diseases has been established by our laboratory and others. Systemic delivery of α-CGRP decreases blood pressure in hypertensive humans, and improves hemodynamic variables in congestive heart failure (CHF) patients. However, the short half-life of the peptide (t 1/2 = ~5.5 min in serum) limits α-CGRP use in any long-term treatment regime. The present study utilized alginate-α-CGRP microcapsules for long-term continuous delivery of α-CGRP in a mouse CHF model. We used an electrospray method to prepare α-CGRP encapsulated alginate microcapsules approximately 200μm in size. The α-CGRP encapsulated microcapsules showed no cytotoxicity when incubated with the cardiac cell lines, HL-1 and H9c2 cells, for 7 days. Subcutaneous administration of microcapsules containing 150, 250, or 500μg α-CGRP lowered the systolic pressure up to 18 h, 3 days, and 7 days, respectively, in wild-type mice (measured by tail-cuff method), indicating that released α-CGRP remains biologically active. The cardioprotective effect of microcapsules released α-CGRP was examined using a transverse aortic constriction (TAC) induced pressure-overload mouse model of CHF. After two days of TAC, 500μl of alginate-α-CGRP microcapsules (containing 150μg α-CGRP) was administered in nine weeks old C57/BL6 mice on alternate days up to 28 days. Echocardiography data showed that microcapsule treatment of α-CGRP significantly preserved left ventricular fraction shortening (FS) and ejection fraction in the TAC mice (FS±SD: sham 47.2±1.5%, sham-alginate-α-CGRP 48.4±1.8%, TAC 29.5±1.4%, and TAC-alginate-α-CGRP 43.2±1.2%). α-CGRP delivery attenuated cardiac hypertrophy in TAC mice when reported as heart wt/tibia length (mg/mm±SD): sham 6.3±0.1, sham-alginate-α-CGRP 6.3±0.2, TAC 8.6±0.3, and TAC-alginate-α-CGRP 6.6±0.2. Alginate-only microcapsules did not affect these cardiac parameters. Our results show that α-CGRP delivery through alginate microcapsules protect hearts from cardiac failure. As alginate is immunologically inactive, the alginate microcapsules offer a new potential delivery paradigm for patients with heart failure.
Alpha-calcitonin gene related peptide (α-CGRP) is a promising neuropeptide for the treatment of c... more Alpha-calcitonin gene related peptide (α-CGRP) is a promising neuropeptide for the treatment of cardiovascular disease. We have developed an alginate biomaterial-based delivery system which increases the peptide’s bioavailability and have shown that subcutaneous delivery of alginate-CGRP microcapsules significantly improved cardiac function in pressure overload-induced heart failure in mice. The goal of this study is to develop efficient alginate microcapsule formulations for oral delivery of α-CGRP. An electrospray method was used to prepare four different formulations of alginate-CGRP microcapsules all of 200 μm diameter- i)- alginate-CGRP microcapsules, ii)- alginate-CGRP microcapsules with UV-light exposure, iii)- poly-L-ornithine (PLO) coated alginate-CGRP microcapsules, and iv)- PLO alginate-CGRP microcapsules with UV-light exposure. The stability of the microcapsules in the digestive tract was evaluated in deionized water, simulated gastric fluid (SGF; pH 1.2), and simulated ...
Congestive heart failure (CHF) is the leading cause of mortality in men and women world-wide, des... more Congestive heart failure (CHF) is the leading cause of mortality in men and women world-wide, despite multiple but limited treatment modalities. Our laboratory and others have established that α-calcitonin gene-related peptide (αCGRP) plays a significant protective role in several cardiovascular diseases. αCGRP is a 37-amino acid neuropeptide and potent vasodilator. In αCGRP-knockout mice, pressure overload significantly exacerbates cardiac hypertrophy, dysfunction and fibrosis. The present study was performed to determine if exogenous delivery of native αCGRP was cardio-protective against pressure overload-induced CHF. Transverse aortic constriction (TAC) was performed to induce pressure overload CHF in nine week old C57/BL6 mice. One group were sham-treated, one TAC alone, and one TAC plus αCGRP (4 mg/kg bwt/day) via an implanted mini-osmotic pump. All mice had serial echocardiography performed and were sacrificed and hearts collected after 28 days. ELISA data showed that αCGRP le...
Alpha-calcitonin gene related peptide (α-CGRP) is a 37-amino acid cardioprotective neuropeptide. ... more Alpha-calcitonin gene related peptide (α-CGRP) is a 37-amino acid cardioprotective neuropeptide. Studies carried out in our laboratory and others establish α-CGRP as a potential therapeutic agent against a variety of cardiovascular diseases. However, the short half-life of α-CGRP limits its use in any long-term treatment regime. The goal of the present study is to develop an α-CGRP agonist analog with extended bioavailability using peptoid chemistry. A peptoid is a N -substituted glycine peptidomimetic molecule and is identical to α-amino acid except that the side chain in a peptoid is attached on the nitrogen rather than the α-carbon atom. Inclusion of a peptoid makes the native peptide protease-resistant and thus biostable in vivo . Using a solid-phase submonomer method, we synthesized a novel human α-CGRP analog containing two monomers of N -methoxyethylglycine (NMEG) peptoid at the N-terminus. Electrospray mass spectrometry (MALDI-TOF) analysis showed that the molecular mass of synthesized peptoid-peptide hybrid, NMEG-α-CGRP, was 4044 that is ~6.7% more than native peptide. An in vitro trypan blue cell exclusion assay demonstrated that incubation of NMEG-α-CGRP (5 μM) for 7 days did not affect the viability of rat H9C2 and mouse HL-1 cardiac cells. To evaluate the biological activity of NMEG-α-CGRP, a subcutaneous injection of human α-CGRP (10 μg/mice) and NMEG-α-CGRP (1, 3, 10, and 30 μg/mice) were given in 9-week-old C57BL6 mice (n=2 mice/dose), and blood pressure (BP) was measured using a tail-cuff method. A dose response curve showed that NMEG-α-CGRP decreased BP in mice in a time-dependent manner. Beginning with and injection of 3 μg of NMEG-α-CGRP, a dip in BP (85 ± 1 mmHg; in ±SD) was observed at 10 min after injection, and BP returned to baseline (125 mmHg) by 6 h, 18 h, and 24 h when injected with 3, 10, and 30 μg doses, respectively. Moreover, 10 μg of human-α-CGRP and NMEG-α-CGRP lowered BP from baseline for 2 h and 18 h, respectively, suggesting that NMEG addition increased stability, and thus bioavailability, of α-CGRP in vivo . In summary, our results show that a NMEG based α-CGRP modification is an effective approach to increase stability and, thus, bioavailability of α-CGRP in vivo making α-CGRP a viable therapeutic drug to treat cardiovascular diseases.
Purpose: Platelet-derived growth factor (PDGF) has previously been shown to influence lens growth... more Purpose: Platelet-derived growth factor (PDGF) has previously been shown to influence lens growth and transparency. The purpose of the present study was to investigate the expression of the PDGF receptor and its mRNA during lens development in chicken embryos. Methods: To examine the expression of PDGF receptor mRNAs, the authors used a combination of polymerase chain reaction, Northern blot analyses, and RNase protection assays. Platelet-derived growth factor receptors were studied using Western blot analyses and immunofluorescence-confocal microscopy. The mitogenic effects of PDGF were assayed using immunochemical detection of 5-bromo-2'-deoxyuridine incorporation into explanted lens epithelia. Results: The authors' studies strongly suggest that the PDGF alpha receptor is the only PDGF receptor present in the embryonic chicken lens during development because they were unable to detect the PDGF beta receptor using two different approaches. Northern blots showed that the chicken lens alpha receptor mRNA is similar in size to the mRNA encoding the human and frog alpha receptor, and Western blots detected a single band with a molecular weight of 170 kDa, close to the reported molecular weight for the human alpha receptor. After staining with specific antibodies, confocal microscopy localized the immunoreactivity to the membranes of the epithelial and annular pad cells. At early stages of development (E6), the PDGF alpha receptor was present throughout the epithelium. At later stages, immunoreactivity was restricted to the peripheral epithelium and the annular pad. The addition of human recombinant PDGF (AA or BB) to tissue cultured E6 chicken lens epithelia sustained cell proliferation significantly better than basal medium alone. Conclusions: The authors' studies provide the first evidence for PDGF alpha receptors in the chicken lens. Localization of these receptors to the peripheral lens epithelium during development and the mitogenic effect of exogenously added PDGF suggest a role for this growth factor in the control of lens growth.
The cardioprotective role of a neuropeptide, alpha-calcitonin gene related peptide (αCGRP), has b... more The cardioprotective role of a neuropeptide, alpha-calcitonin gene related peptide (αCGRP), has been established in a variety of cardiovascular diseases. To increase the bioavailability of the circulating peptide, we created a peptide delivery system by encapsulating αCGRP in an alginate biopolymer and showed that subcutaneous delivery of alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) on alternate days, up to 28 days, significantly protected hearts at pathophysiological levels in a transverse aortic constriction (TAC) pressure-overload induced heart failure murine model. The present study was performed to determine if weekly subcutaneous delivery of alginate-αCGRP microcapsules exhibited similar cardioprotective effects in TAC-mice as observed in our previous study with alternate days dose delivery scheme. This study is crucial to shed light on the efficacy of these microcapsules. An electrospray method was used to prepare alginate-αCGRP microcapsules of 200 μm diameter. Male C57BL6 mice were divided into four groups (3 mice/group): i- sham, ii- sham-alginate-CGRP, iii- TAC, and iv- TAC-alginate-CGRP. Mice from TAC and TAC-alginate-CGRP groups underwent TAC procedure. Two days post-TAC, alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) were administered subcutaneously once a week, up to 4 weeks, in the respective alginate-CGRP groups of mice. Short-axis echocardiography was performed to evaluate cardiac functions. After 28 days of microcapsules delivery, calculated percent fractional shortening (FS) and ejection fraction (EF) in mice were (in ±SD)- sham: FS= 47.6 ± 0.9, EF= 79.8 ± 0.9; sham-alginate-CGRP: FS= 47.3 ± 1.9, EF= 79.1 ± 2; TAC: FS= 34.1 ± 4.7, EF= 63.6 ± 7.1; TAC-alginate-CGRP: FS= 32.2 ± 2.3, EF= 61.0 ± 3.4. These echo data demonstrate that TAC heart failure mice had the usual significantly reduced cardiac functions, however weekly delivery of alginate-αCGRP microcapsules showed no improvement in heart performance in the TAC-mice. Combined results from our present and previous studies suggested that alginate-αCGRP microcapsules delivery on alternate days, but not weekly, is the most efficacious choice to achieve cardioprotective effects of αCGRP against pressure-induced heart failure in mice.
The embryonic lens contains two populations of cells, lens epithelial cells and lens fiber cells.... more The embryonic lens contains two populations of cells, lens epithelial cells and lens fiber cells. As the growth of the human lens is linear from the age of 10 to 90, lens epithelial cells divide and differentiate into fiber cells at a uniform rate during adulthood. Any defects that arise during fiber formation will remain in the lens. We postulate that regulation of early lens growth is critical for the onset of cataracts that usually occur later in life. Slowing the growth of the lens could therefore provide a strategy to suppress the formation of cataracts. However, the factor(s) that control lens growth in vivo have not been identified.We have identified 18 receptor and cytoplasmic kinases present in lens epithelial cells. Using these as potential targets for factors controlling growth, we tested corresponding ligands in a lens epithelial cell proliferation assay. Platelet-derived growth factor (PDGF) proved to promote a growth activity similar to, but distinct from, that of embryo serum.
Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indi... more Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
Introduction: Calcitonin gene-related peptide (CGRP), a 37 amino acid neuropeptide, is a potent v... more Introduction: Calcitonin gene-related peptide (CGRP), a 37 amino acid neuropeptide, is a potent vasodilator, and plays a critical role in the efferent functions of the sensory nervous system. A protective role for CGRP in cardiovascular diseases (hypertension, cardiac ischemia, and failure) has been well established by our laboratory and others. In the present study we determined whether long-term exogenous administration of α-CGRP protects against pressure-induced heart failure. Method: Three groups of nine-week-old C57/BL6 mice were studied: one group received a sham procedure (n= 4) and two groups underwent transverse aortic constriction (TAC). Two days after TAC, one group had CGRP-filled osmotic pumps (4 mg/kg bwt/day) implanted subcutaneously (n= 7) while the second group was TAC-only (n=6). At day 28, all groups had echocardiography performed and were sacrificed and heart tissue collected. Results: Echocardiographic and histological data showed that TAC markedly decreased fractional shortening (FS) and ejection fraction and increased heart and lung weight, cardiac hypertrophy, and fibrosis compared to sham. However, the TAC-CGRP mice had preserved cardiac function and less cardiac fibrosis (FS ±SEM: sham 46.2±1.8% vs TAC 25.4±1.1%, p < 0.001; and TAC 25.4±1.1% vs TAC-CGRP 36.6±1.2%, p < 0.001). CGRP significantly reduced apoptotic cell death and lipid peroxidation (an oxidative stress marker measured by malondialdehyde and 4-HNE staining) in the TAC hearts [malondialdehyde (nmol/mg protein) ±SEM: sham 3.5±0.19 vs TAC 14.3±0.57, p < 0.05; and TAC 14.3±0.57 vs TAC-CGRP 5.5±0.12, p < 0.05]. TAC alone decreased the level of p-ERK1/2 and increased p-JNK compared to sham. CGRP-TAC hearts had higher p-ERK1/2 levels but equal p-JNK levels compared to the TAC hearts. HIF1α and nrf2 protein levels were not different between experimental groups. Compared to TAC hearts, TAC-CGRP hearts had lower p-AMPK and nuclear Sirt1 level, regulatory proteins of energy metabolism. Conclusion: Our results suggest that CGRP, mediated through energy metabolic, and oxidative stress pathways, decreases myocyte apoptosis and is protective in pressure-induced heart failure. Thus, CGRP is a potential therapeutic agent in preventing the progression of heart failure.
The cardioprotective role of α-calcitonin gene related peptide (α-CGRP), a 37-amino acid neuropep... more The cardioprotective role of α-calcitonin gene related peptide (α-CGRP), a 37-amino acid neuropeptide and potent vasodilator, in cardiac diseases has been established by our laboratory and others. Systemic delivery of α-CGRP decreases blood pressure in hypertensive humans, and improves hemodynamic variables in congestive heart failure (CHF) patients. However, the short half-life of the peptide (t 1/2 = ~5.5 min in serum) limits α-CGRP use in any long-term treatment regime. The present study utilized alginate-α-CGRP microcapsules for long-term continuous delivery of α-CGRP in a mouse CHF model. We used an electrospray method to prepare α-CGRP encapsulated alginate microcapsules approximately 200μm in size. The α-CGRP encapsulated microcapsules showed no cytotoxicity when incubated with the cardiac cell lines, HL-1 and H9c2 cells, for 7 days. Subcutaneous administration of microcapsules containing 150, 250, or 500μg α-CGRP lowered the systolic pressure up to 18 h, 3 days, and 7 days, respectively, in wild-type mice (measured by tail-cuff method), indicating that released α-CGRP remains biologically active. The cardioprotective effect of microcapsules released α-CGRP was examined using a transverse aortic constriction (TAC) induced pressure-overload mouse model of CHF. After two days of TAC, 500μl of alginate-α-CGRP microcapsules (containing 150μg α-CGRP) was administered in nine weeks old C57/BL6 mice on alternate days up to 28 days. Echocardiography data showed that microcapsule treatment of α-CGRP significantly preserved left ventricular fraction shortening (FS) and ejection fraction in the TAC mice (FS±SD: sham 47.2±1.5%, sham-alginate-α-CGRP 48.4±1.8%, TAC 29.5±1.4%, and TAC-alginate-α-CGRP 43.2±1.2%). α-CGRP delivery attenuated cardiac hypertrophy in TAC mice when reported as heart wt/tibia length (mg/mm±SD): sham 6.3±0.1, sham-alginate-α-CGRP 6.3±0.2, TAC 8.6±0.3, and TAC-alginate-α-CGRP 6.6±0.2. Alginate-only microcapsules did not affect these cardiac parameters. Our results show that α-CGRP delivery through alginate microcapsules protect hearts from cardiac failure. As alginate is immunologically inactive, the alginate microcapsules offer a new potential delivery paradigm for patients with heart failure.
Alpha-calcitonin gene related peptide (α-CGRP) is a promising neuropeptide for the treatment of c... more Alpha-calcitonin gene related peptide (α-CGRP) is a promising neuropeptide for the treatment of cardiovascular disease. We have developed an alginate biomaterial-based delivery system which increases the peptide’s bioavailability and have shown that subcutaneous delivery of alginate-CGRP microcapsules significantly improved cardiac function in pressure overload-induced heart failure in mice. The goal of this study is to develop efficient alginate microcapsule formulations for oral delivery of α-CGRP. An electrospray method was used to prepare four different formulations of alginate-CGRP microcapsules all of 200 μm diameter- i)- alginate-CGRP microcapsules, ii)- alginate-CGRP microcapsules with UV-light exposure, iii)- poly-L-ornithine (PLO) coated alginate-CGRP microcapsules, and iv)- PLO alginate-CGRP microcapsules with UV-light exposure. The stability of the microcapsules in the digestive tract was evaluated in deionized water, simulated gastric fluid (SGF; pH 1.2), and simulated ...
Congestive heart failure (CHF) is the leading cause of mortality in men and women world-wide, des... more Congestive heart failure (CHF) is the leading cause of mortality in men and women world-wide, despite multiple but limited treatment modalities. Our laboratory and others have established that α-calcitonin gene-related peptide (αCGRP) plays a significant protective role in several cardiovascular diseases. αCGRP is a 37-amino acid neuropeptide and potent vasodilator. In αCGRP-knockout mice, pressure overload significantly exacerbates cardiac hypertrophy, dysfunction and fibrosis. The present study was performed to determine if exogenous delivery of native αCGRP was cardio-protective against pressure overload-induced CHF. Transverse aortic constriction (TAC) was performed to induce pressure overload CHF in nine week old C57/BL6 mice. One group were sham-treated, one TAC alone, and one TAC plus αCGRP (4 mg/kg bwt/day) via an implanted mini-osmotic pump. All mice had serial echocardiography performed and were sacrificed and hearts collected after 28 days. ELISA data showed that αCGRP le...
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Papers by Jay Potts