Programmed death-1 mediates venous neointimal hyperplasia in humans and rats

FoxO1 is a negative regulator of neointimal hyperplasia in a rat model of patch angioplasty

Neointimal hyperplasia persists as a barrier following vascular interventions. Forkhead Box O1 (FoxO1) is a transcription factor that possesses a distinctive fork head domain and indirectly contributes to various physiological processes. FoxO1 expression and signaling also impact the energy metabolism of vascular smooth muscle cells, potentially influencing neointimal hyperplasia. Our hypothesis is that FoxO1 inhibits neointimal hyperplasia in a rat patch angioplasty model. Four groups were compared in a rat aorta patch angioplasty model: the control group without treatment, patches coated with AS184286 (a FoxO1 inhibitor) in a PLGA matrix, patches coated with FoxO1 in a PLGA matrix, and patches coated with MLN0905 (a PLK1 inhibitor) in a PLGA matrix. The patches were harvested on Day 14 and subjected to analysis. FoxO1-positive and p-FoxO1 cells were observed after patch angioplasty. The addition of FoxO1 through patches coated with exogenous FoxO1 protein in a PLGA matrix significantly inhibited neointimal thickness (p = 0.0012). The treated groups exhibited significantly lower numbers of CD3 (p = 0.0003), CD45 (p < 0.0001), and PCNA (p < 0.0001)-positive cells. PLK1 is an upstream transcriptional regulator of FoxO1, governing the expression and function of FoxO1. MLN0905 PLGA-coated patches exhibited comparable reductions in neointimal thickness and inflammatory cell accumulation. FoxO1 represents a promising therapeutic strategy for inhibiting neointimal hyperplasia.

Delivery of rivaroxaban and chitosan rapamycin microparticle with dual antithrombosis and antiproliferation functions inhibits venous neointimal hyperplasia

Neointimal hyperplasia is a complex process after vascular interventions, acute platelet deposition and smooth muscle cell proliferation both contributed to this process. There are still no perfect solutions to solve this problem. Rivaroxaban is a novel anticoagulant that has been widely used in clinic, it has a good pharmacological effects both in vivo and in vitro. Chitosan microparticle rapamycin (MP-rapa) was fabricated, interspaces of polyglycolic acid (PGA) scaffold were used as a reservoir of MP-rapa, and the scaffold was coated with hyaluronic acid rivaroxaban (MP-rapa-riva). Scanning electronic microscopy (SEM) photographs were taken and water contact angles were measured, rat inferior vena cava (IVC) patch venoplasty model was used; patches were harvested at day 14 and examined by immunohistochemistry and immunofluorescence. SEM photographs showed the microparticles rapamycin were inside the interspace of the scaffold, hyaluronic acid rivaroxaban was also successfully coated onto the surface of the scaffold. There was a thinner neointima, fewer proliferating cell nuclear antigen (PCNA) positive cells, fewer macrophages in the MP-rapa and MP-rapa-riva grafts compared to the control PGA graft. The result showed that this scaffold with dual anticoagulation and antiproliferation functions can effectively inhibit venous neointimal hyperplasia, although this is an animal experiment, it showed promising potential clinical application in the future.

Tailoring ZE21B Alloy with Nature-Inspired Extracellular Matrix Secreted by Micro-Patterned Smooth Muscle Cells and Endothelial Cells to Promote Surface Biocompatibility

Delayed surface endothelialization is a bottleneck that restricts the further application of cardiovascular stents. It has been reported that the nature-inspired extracellular matrix (ECM) secreted by the hyaluronic acid (HA) micro-patterned smooth muscle cells (SMC) and endothelial cells (EC) can significantly promote surface endothelialization. However, this ECM coating obtained by decellularized method (dECM) is difficult to obtain directly on the surface of degradable magnesium (Mg) alloy. In this study, the method of obtaining bionic dECM by micro-patterning SMC/EC was further improved, and the nature-inspired ECM was prepared onto the Mg-Zn-Y-Nd (ZE21B) alloy surface by self-assembly. The results showed that the ECM coating not only improved surface endothelialization of ZE21B alloy, but also presented better blood compatibility, anti-hyperplasia, and anti-inflammation functions. The innovation and significance of the study is to overcome the disadvantage of traditional dECM coating and further expand the application of dECM coating to the surface of degradable materials and materials with different shapes.

Biodegraded PCl and gelatin fabricated vascular patch in rat aortic and inferior vena cava angioplasty

Novel synthetic prosthesis materials for patch angioplasty are continuously under development and optimization. When a nonwoven-based gelatin membrane is coupled with an electrospun layer of polycaprolactone (PCL), these biohybrid polymer membranes (BHMs) possess higher mechanical properties in aqueous environments. We hypothesized that BHMs can also be used as vascular patches, and we tested our hypothesis in a rat IVC venoplasty and aortic arterioplasty model. Patch venoplasty and arterioplasty were performed in SD rats (200 g), the patches were harvested at day 14, and samples were analyzed by immunohistochemistry and immunofluorescence. The BHM patches were almost degraded, with few parts remaining after 14 days. There was a line of CD34- and nestin-positive cells on the endothelium, with some cells were CD34 and nestin dual-positive, macrophages and leukocytes also participated in the patch healing process. There were PCNA-positive cells in the neointima and peri-patch area, with some cells were also PCNA and α-actin dual-positive. Arterial neointimal endothelial cells were Ephrin-B2- and dll-4-positive, and venous neointimal endothelial cells were Eph-B4- and COUP-TFII-positive. BHM shares a similar healing process like other patch materials, and BHM may have potential applications in vascular surgery.

A Novel Plant Leaf Patch Absorbed With IL-33 Antibody Decreases Venous Neointimal hyperplasia

Introduction: We recently showed that a decellularized leaf scaffold can be loaded with polylactic-co-glycolic acid (PLGA)-based rapamycin nanoparticles, this leaf patch can then inhibit venous neointimal hyperplasia in a rat inferior vena cava (IVC) venoplasty model. IL-33 plays a role in the neointimal formation after vascular injury. We hypothesized that plant leaves can absorb therapeutic drug solution and can be used as a patch with drug delivery capability, and plant leaves absorbed with IL-33 antibody can decrease venous neointimal hyperplasia in the rat IVC venoplasty model. Method: A human spiral saphenous vein (SVG) graft implanted in the popliteal vein was harvested from a patient with trauma and analyzed by immunofluorescence. Male Sprague-Dawley rats (aged 6-8 weeks) were used to create the IVC patch venoplasty model. Plant leaves absorbed with rhodamine, distilled water (control), rapamycin, IL-33, and IL-33 antibody were cut into patches (3 × 1.5 mm²) and implanted into the rat IVC. Patches were explanted at day 14 for analysis. Result: At day 14, in the patch absorbed with rhodamine group, immunofluorescence showed rhodamine fluorescence in the neointima, inside the patch, and in the adventitia. There was a significantly thinner neointima in the plant patch absorbed with rapamycin (p = 0.0231) compared to the patch absorbed with distilled water. There was a significantly large number of IL-33 (p = 0.006) and IL-1β (p = 0.012) positive cells in the human SVG neointima compared to the human great saphenous vein. In rats, there was a significantly thinner neointima, a smaller number of IL-33 (p = 0.0006) and IL-1β (p = 0.0008) positive cells in the IL-33 antibody-absorbed patch group compared to the IL-33-absorbed patch group. Conclusion: We found that the natural absorption capability of plant leaves means they can absorb drug solution efficiently and can also be used as a novel drug delivery system and venous patch. IL-33 plays a role in venous neointimal hyperplasia both in humans and rats; neutralization of IL-33 by IL-33 antibody can be a therapeutic method to decrease venous neointimal hyperplasia.

Biomimetic Elastin Fiber Patch in Rat Aorta Angioplasty

Introduction: Vascular grafts significantly contribute to advances in vascular surgery, but none of the currently available prosthetic grafts have elastin fibers similar to native arteries. We hypothesized that a novel elastin patch could be produced after a rat decellularized thoracic aorta elastin fiber scaffold is implanted subcutaneously in rats; we tested this novel elastin patch in a rat aortic arterioplasty model. Methods: Sprague-Dawley rats (200 g) were used. Rat thoracic aortae were decellularized and sectioned at a thickness of 30 μm. A single elastin fiber scaffold was fabricated as a net (5 × 5 mm²), and then a three-layer scaffold was constructed to make a new patch. The hyaluronic acid-sodium alginate (HA/SA) hydrogel was fabricated by reacting sodium SA, HA, and CaCO₃, and then the hydrogel was added to the patch to secure the elastin fibers. The patches were implanted subcutaneously in rats and harvested at day 14. The elastin patches were then implanted into the same rat's aorta and harvested at day 14; a decellularized rat thoracic aorta (TA) patch was used as a control. Sections of the retrieved patches were stained by immunohistochemistry and immunofluorescence. Results: The elastin fibers could be secured by the hydrogel. After 14 days, the subcutaneously implanted elastin patch was incorporated into the rat tissue, and H&E staining showed that new tissue had formed around the elastin patch with almost no hydrogel left. After implantation into the rat aorta and then retrieval on day 14, H&E staining showed that there was neointima and adventitia formation in both the TA and elastin patch groups. Both patches showed a similar histological structure after implantation, and immunofluorescence showed that there were CD34- and nestin-positive cells in the neointima. In both groups, the endothelial cells expressed the arterial identity markers Ephrin-B2 and dll-4; almost one-third of the cells in the neointima were PCNA-positive with rare cleaved caspase-3-positive cells. Conclusion: We demonstrated a novel approach to making elastin fiber scaffold hydrogel patches (elastin patches) and tested them in a rat aorta arterioplasty model. This patch showed a similar healing process as the decellularized TA patch; it also showed potential applications in large animals and may be a substitute for prosthetic grafts in vascular surgery.

The application of tissue-engineered fish swim bladder vascular graft

Small diameter (< 6 mm) prosthetic vascular grafts continue to show very low long-term patency, but bioengineered vascular grafts show promising results in preclinical experiments. To assess a new scaffold source, we tested the use of decellularized fish swim bladder as a vascular patch and tube in rats. Fresh goldfish (Carassius auratus) swim bladder was decellularized, coated with rapamycin and then formed into patches or tubes for implantation in vivo. The rapamycin-coated patches showed decreased neointimal thickness in both the aorta and inferior vena cava patch angioplasty models. Rapamycin-coated decellularized swim bladder tubes implanted into the aorta showed decreased neointimal thickness compared to uncoated tubes, as well as fewer macrophages. These data show that the fish swim bladder can be used as a scaffold source for tissue-engineering vascular patches or vessels.

Bai et al. employ a fish bladder-derived decellularized matrix for the engineering of vascular grafts. The authors show that rapamycin-coated bladder-derived vascular grafts can be implanted as an interposition graft in rats, and that these vascular grafts showed decreased neointimal thickness both in artery and veins.