Injectable nanoclay gels for angiogenesis

AbstractThe retention and sustained activity of therapeutic proteins at delivery sites are goals of regenerative medicine. Vascular endothelial growth factor (VEGF) has significant potential in promoting the growth and regeneration of blood vessels but is intrinsically labile. This is exacerbated by the inflammatory microenvironments at sites requiring regeneration. For VEGF to be efficacious it may require a carrier that stabilises it, protects it from degradation and retains it at a site of interest. In this study we tested the hypothesis that injectable nanoclay gels composed of Laponite XLG can stabilise VEGF and retain it in active form for therapeutic delivery. To achieve this, VEGF was incorporated in Laponite gels and its activity tested at a range of concentrations using in vivo cell culture tubulogenesis assays and in vivo angiogenesis assays. We found that VEGF-Laponite gels enhanced tubulogenesis in a dose-dependent manner in vivo. When administered subcutaneously in vivo Laponite was retained at an injection site for up to a period of three weeks and promoted a 4-fold increase in blood vessel formation compared with alginate or vehicle controls as confirmed by CD31 staining. Notably, in contrast to alginate, Laponite gels did not release VEGF, indicating a strong interaction between the growth factor and the nanoclay, and suggesting that Laponite enhancement of VEGF efficacy is due to its retention at an implantation site over a prolonged period. Our approach provides a robust method for delivery of bioactive recombinant VEGF without the necessity for complex hydrogel or protein engineering.

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Follicle-Stimulating Hormone and Luteinizing Hormone/Chorionic Gonadotropin Stimulation of Vascular Endothelial Growth Factor Production by Macaque Granulosa Cells from Pre- and Periovulatory Follicles1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.82.7.4169 ◽

1997 ◽

Vol 82 (7) ◽

pp. 2135-2142

Author(s):

Lane K. Christenson ◽

Richard L. Stouffer

Keyword(s):

Vascular Endothelial Growth Factor ◽

Growth Factor ◽

Granulosa Cells ◽

Dependent Manner ◽

Vascular Endothelial ◽

Progesterone Production ◽

Endothelial Growth Factor ◽

In Vitro Treatment

Granulosa cells in the ovulatory follicle express messenger ribonucleic acid encoding vascular endothelial growth factor (VEGF), an agent that may mediate the neovascularization of the developing corpus luteum, but it is not known whether luteinizing granulosa cells synthesize and secrete VEGF during the periovulatory interval. Studies were designed to evaluate the effects of an in vivo gonadotropin surge on VEGF production by macaque granulosa cells (study 1) and to test the hypothesis that gonadotropins act directly on granulosa cells to regulate VEGF production (study 2). Monkeys received a regimen of exogenous gonadotropins to promote the development of multiple preovulatory follicles. Nonluteinized granulosa cells (i.e. preovulatory; NLGC) and luteinized granulosa cells (i.e. periovulatory; LGC) were aspirated from follicles before and 27 h after an ovulatory gonadotropin bolus, respectively. Cells were either incubated for 24 h in medium with or without 100 ng/mL hCG (study 1) or cultured for 6 days in medium with or without 100 ng/mL hCG or 0.1, 1, 10, and 100 ng/mL of recombinant human LH (r-hLH) or r-hFSH (study 2). Culture medium was assayed for VEGF and progesterone. In study 1, LGC produced 8-fold greater levels of VEGF than NLGC (899 ± 471 vs. 111 ± 26 pg/mL, mean ± sem; P < 0.05). In vitro treatment with hCG increased (P < 0.05) VEGF production by NLGC to levels that were not different from the LGC incubated under control conditions. In vivo bolus doses of r-hCG (100 and 1000 IU) and r-hFSH (2500 IU) were equally effective in elevating granulosa cell VEGF production. In study 2, in vitro treatment with r-hFSH, r-hLH, and hCG markedly increased (P< 0.05) VEGF and progesterone production by the NLGC in a dose- and time-dependent manner. By comparison, the three gonadotropins (100 ng/mL dose) only modestly increased VEGF and progesterone production by LGC. These experiments demonstrate a novel role for the midcycle surge of gonadotropin (LH/CG or FSH) in primates to promote VEGF production by granulosa cells in the periovulatory follicle. Further, the data demonstrate that FSH-like as well as LH-like gonadotropins directly stimulate VEGF synthesis by granulosa cells.

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Ligation of CD40 induces the expression of vascular endothelial growth factor by endothelial cells and monocytes and promotes angiogenesis in vivo

Blood ◽

10.1182/blood.v96.12.3801.h8003801_3801_3808 ◽

2000 ◽

Vol 96 (12) ◽

pp. 3801-3808 ◽

Cited By ~ 2

Author(s):

Michael Melter ◽

Marlies E. J. Reinders ◽

Masayuki Sho ◽

Soumitro Pal ◽

Christopher Geehan ◽

...

Keyword(s):

Vascular Endothelial Growth Factor ◽

Endothelial Cells ◽

Growth Factor ◽

Luciferase Reporter ◽

Ribonuclease Protection Assay ◽

Dependent Manner ◽

Vascular Endothelial ◽

Vegf Expression ◽

Endothelial Growth Factor

This study addresses a mechanism by which lymphocytes may promote vascular endothelial growth factor (VEGF) expression and angiogenesis in immune inflammation. Resting human umbilical endothelial cells (HUVECs) were found to express low levels of VEGF messenger RNA (mRNA) by reverse transcription polymerase chain reaction and ribonuclease protection assay with little or no change in expression following activation by cytokines, including tumor necrosis factor-α, interleukin (IL)–1, interferon γ, or IL-4. In contrast, treatment of HUVECs and monocytes with soluble CD40 ligand (sCD40L) resulted in a marked dose-dependent induction of VEGF mRNA (approximately 4-fold), which peaked between 1 and 5 hours post-stimulation. Transient transfection of HUVECs was performed with a luciferase reporter construct under the control of the human VEGF promoter. Treatment of transfected HUVECs with sCD40L was found to enhance luciferase activity (approximately 4-fold) compared with controls, similar to the relative fold induction in mRNA expression in parallel cultures. Thus, CD40-dependent VEGF expression was a result of transcriptional control mechanisms. Treatment of HUVECs with sCD40L was also found to function in vitro to promote growth and proliferation in a VEGF-dependent manner, and CD40-dependent HUVEC growth was comparable to that found following treatment with recombinant human VEGF. Furthermore, subcutaneous injection of sCD40L in severe combined immunodeficient and nude mice induced VEGF expression and marked angiogenesis in vivo. Taken together, these findings are consistent with a function for CD40L-CD40 interactions in VEGF-induced angiogenesis and define a mechanistic link between the immune response and angiogenesis.

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Dynamic phosphorylation of VE-cadherin Y685 throughout mouse estrous cycle in ovary and uterus

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00773.2013 ◽

2014 ◽

Vol 307 (3) ◽

pp. H448-H454 ◽

Cited By ~ 4

Author(s):

Adama Sidibé ◽

Helena Polena ◽

Jeremy Razanajatovo ◽

Tiphaine Mannic ◽

Nicolas Chaumontel ◽

...

Keyword(s):

Vascular Endothelial Growth Factor ◽

Growth Factor ◽

Tyrosine Phosphorylation ◽

Estrous Cycle ◽

Vascular Remodeling ◽

Female Reproductive Tract ◽

Dependent Manner ◽

Vascular Endothelial ◽

Endothelial Growth Factor

We previously reported that vascular endothelial growth factor induced vascular endothelial (VE)-cadherin tyrosine phosphorylation at Y685 in a Src-dependent manner in vitro. Here, we studied the occurrence of Y685 phosphorylation in vivo in the female reproductive tract because it is a unique model of physiological vascular remodeling dependent on vascular endothelial growth factor. We first developed and characterized an anti-phospho-specific antibody against the site Y685 of VE-cadherin to monitor VE-cadherin phosphorylation along the four phases of mouse estrous cycle, termed proestrus, estrus, metestrus, and diestrus. A dynamic profile of tyrosine phosphorylated proteins was observed in both uterus and ovary throughout mouse estrous cycle, including kinase Src, which was found highly active at the estrus phase. The extent of tyrosine phosphorylated VE-cadherin was low at proestrus but strongly increased at estrus and returned to baseline at metestrus and diestrus, suggesting a potent hormonal regulation of this specific process. Indeed, C57Bl/6 female mice treatment with pregnant mare serum gonadotropin and human chorionic gonadotropin confirmed a significant increase in phosphoY685-VE-cadherin compared with that in untreated mice. These results demonstrate that VE-cadherin tyrosine phosphorylation at Y685 is a physiological and hormonally regulated process in female reproductive organs. In addition, this process was concomitant with the early steps of vascular remodeling taking place at estrus stage, suggesting that phosphoY685-VE-cadherin is a biomarker of endothelial cell activation in vivo.

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Ligation of CD40 induces the expression of vascular endothelial growth factor by endothelial cells and monocytes and promotes angiogenesis in vivo

Blood ◽

10.1182/blood.v96.12.3801 ◽

2000 ◽

Vol 96 (12) ◽

pp. 3801-3808 ◽

Cited By ~ 129

Author(s):

Michael Melter ◽

Marlies E. J. Reinders ◽

Masayuki Sho ◽

Soumitro Pal ◽

Christopher Geehan ◽

...

Keyword(s):

Vascular Endothelial Growth Factor ◽

Endothelial Cells ◽

Growth Factor ◽

Luciferase Reporter ◽

Ribonuclease Protection Assay ◽

Dependent Manner ◽

Vascular Endothelial ◽

Vegf Expression ◽

Endothelial Growth Factor

Abstract This study addresses a mechanism by which lymphocytes may promote vascular endothelial growth factor (VEGF) expression and angiogenesis in immune inflammation. Resting human umbilical endothelial cells (HUVECs) were found to express low levels of VEGF messenger RNA (mRNA) by reverse transcription polymerase chain reaction and ribonuclease protection assay with little or no change in expression following activation by cytokines, including tumor necrosis factor-α, interleukin (IL)–1, interferon γ, or IL-4. In contrast, treatment of HUVECs and monocytes with soluble CD40 ligand (sCD40L) resulted in a marked dose-dependent induction of VEGF mRNA (approximately 4-fold), which peaked between 1 and 5 hours post-stimulation. Transient transfection of HUVECs was performed with a luciferase reporter construct under the control of the human VEGF promoter. Treatment of transfected HUVECs with sCD40L was found to enhance luciferase activity (approximately 4-fold) compared with controls, similar to the relative fold induction in mRNA expression in parallel cultures. Thus, CD40-dependent VEGF expression was a result of transcriptional control mechanisms. Treatment of HUVECs with sCD40L was also found to function in vitro to promote growth and proliferation in a VEGF-dependent manner, and CD40-dependent HUVEC growth was comparable to that found following treatment with recombinant human VEGF. Furthermore, subcutaneous injection of sCD40L in severe combined immunodeficient and nude mice induced VEGF expression and marked angiogenesis in vivo. Taken together, these findings are consistent with a function for CD40L-CD40 interactions in VEGF-induced angiogenesis and define a mechanistic link between the immune response and angiogenesis.

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