Application of the Tissue-Engineered Plant Scaffold as a Vascular Patch

Recent advances in plant-derived polysaccharide scaffolds in tissue engineering: A review

As a natural three-dimensional biopolymer, decellularized plant-derived scaffolds usually comprise various polysaccharides, mostly cellulose, pectin, and hemicellulose. They are characterized by natural biocompatibility and porous structures. The emergence of decellularized purified polysaccharide scaffolds provides an attractive method to overcome the challenges associated with nutrient delivery and biocompatibility, as they serve as optimal non-immune environments for stem cell adhesion and proliferation. To date, limited corresponding literature is available to systemically summarize the development and potential of these scaffolds in tissue engineering. Therefore, the current review summarized the biomimetic properties of plant-derived polysaccharide scaffolds and the latest progress in tissue engineering applications. This review first discusses the advantages of decellularized plant-derived polysaccharide scaffolds by briefly introducing their features and current limitations in clinical applications. Subsequently, the latest progress in emerging applications of regenerative biomaterials is reviewed, followed by a discussion of the studies on the interactions of biomaterials with cells and tissues. Finally, challenges in obtaining reliable scaffolds and possible future directions are discussed.

Advances in medical polyesters for vascular tissue engineering

Blood vessels are highly dynamic and complex structures with a variety of physiological functions, including the transport of oxygen, nutrients, and metabolic wastes. Their normal functioning involves the close and coordinated cooperation of a variety of cells. However, adverse internal and external environmental factors can lead to vascular damage and the induction of various vascular diseases, including atherosclerosis and thrombosis. This can have serious consequences for patients, and there is an urgent need for innovative techniques to repair damaged blood vessels. Polyesters have been extensively researched and used in the treatment of vascular disease and repair of blood vessels due to their excellent mechanical properties, adjustable biodegradation time, and excellent biocompatibility. Given the high complexity of vascular tissues, it is still challenging to optimize the utilization of polyesters for repairing damaged blood vessels. Nevertheless, they have considerable potential for vascular tissue engineering in a range of applications. This summary reviews the physicochemical properties of polyhydroxyalkanoate (PHA), polycaprolactone (PCL), poly-lactic acid (PLA), and poly(lactide-co-glycolide) (PLGA), focusing on their unique applications in vascular tissue engineering. Polyesters can be prepared not only as 3D scaffolds to repair damage as an alternative to vascular grafts, but also in various forms such as microspheres, fibrous membranes, and nanoparticles to deliver drugs or bioactive ingredients to damaged vessels. Finally, it is anticipated that further developments in polyesters will occur in the near future, with the potential to facilitate the wider application of these materials in vascular tissue engineering.

Unconventional strategies for liver tissue engineering: plant, paper, silk and nanomaterial-based scaffolds

The paper highlights how significant characteristics of liver can be modeled in tissue-engineered constructs using unconventional scaffolds. Hepatic lobular organization and metabolic zonation can be mimicked with decellularized plant structures with vasculature resembling a native-hepatic lobule vascular arrangement or silk blend scaffolds meticulously designed for guided cellular arrangement as hepatic patches or metabolic activities. The functionality of hepatocytes can be enhanced and maintained for long periods in naturally fibrous structures paving way for bioartificial liver development. The phase I enzymatic activity in hepatic models can be raised exploiting the microfibrillar structure of paper to allow cellular stacking creating hypoxic conditions to induce in vivo-like xenobiotic metabolism. Lastly, the paper introduces amalgamation of carbon-based nanomaterials into existing scaffolds in liver tissue engineering.

From Nature to Technology: Exploring the Potential of Plant-Based Materials and Modified Plants in Biomimetics, Bionics, and Green Innovations

This review explores the extensive applications of plants in areas of biomimetics and bioinspiration, highlighting their role in developing sustainable solutions across various fields such as medicine, materials science, and environmental technology. Plants not only serve essential ecological functions but also provide a rich source of inspiration for innovations in green nanotechnology, biomedicine, and architecture. In the past decade, the focus has shifted towards utilizing plant-based and vegetal waste materials in creating eco-friendly and cost-effective materials with remarkable properties. These materials are employed in making advancements in drug delivery, environmental remediation, and the production of renewable energy. Specifically, the review discusses the use of (nano)bionic plants capable of detecting explosives and environmental contaminants, underscoring their potential in improving quality of life and even in lifesaving applications. The work also refers to the architectural inspirations drawn from the plant world to develop novel design concepts that are both functional and aesthetic. It elaborates on how engineered plants and vegetal waste have been transformed into value-added materials through innovative applications, especially highlighting their roles in wastewater treatment and as electronic components. Moreover, the integration of plants in the synthesis of biocompatible materials for medical applications such as tissue engineering scaffolds and artificial muscles demonstrates their versatility and capacity to replace more traditional synthetic materials, aligning with global sustainability goals. This paper provides a comprehensive overview of the current and potential uses of living plants in technological advancements, advocating for a deeper exploration of vegetal materials to address pressing environmental and technological challenges.

Plant Decellularization by Chemical and Physical Methods for Regenerative Medicine: A Review Article

Fabricating three-dimensional (3D) scaffolds is attractive due to various advantages for tissue engineering, such as cell migration, proliferation, and adhesion. Since cell growth depends on transmitting nutrients and cell residues, naturally vascularized scaffolds are superior for tissue engineering. Vascular passages help the inflow and outflow of liquids, nutrients, and waste disposal from the scaffold and cell growth. Porous scaffolds can be prepared by plant tissue decellularization which allows for the cultivation of various cell lines depending on the intended application. To this end, researchers decellularize plant tissues by specific chemical and physical methods. Researchers use plant parts depending on their needs, for example, decellularizing the leaves, stems, and fruits. Plant tissue scaffolds are advantageous for regenerative medicine, wound healing, and bioprinting. Studies have examined various plants such as vegetables and fruits such as orchid, parsley, spinach, celery, carrot, and apple using various materials and techniques such as sodium dodecyl sulfate, Triton X-100, peracetic acid, deoxyribonuclease, and ribonuclease with varying percentages, as well as mechanical and physical techniques like freeze-thaw cycles. The process of data selection, retrieval, and extraction in this review relied on scholarly journal publications and other relevant papers related to the subject of decellularization, with a specific emphasis on plant-based research. The obtained results indicate that, owing to the cellulosic structure and vascular nature of the decellularized plants and their favorable hydrophilic and biological properties, they have the potential to serve as biological materials and natural scaffolds for the development of 3D-printing inks and scaffolds for tissue engineering.

Bioprocessing by Decellularized Scaffold Biomaterials in Cultured Meat: A Review

As novel carrier biomaterials, decellularized scaffolds have promising potential in the development of cellular agriculture and edible cell-cultured meat applications. Decellularized scaffold biomaterials have characteristics of high biocompatibility, bio-degradation, biological safety and various bioactivities, which could potentially compensate for the shortcomings of synthetic bio-scaffold materials. They can provide suitable microstructure and mechanical support for cell adhesion, differentiation and proliferation. To our best knowledge, the preparation and application of plant and animal decellularized scaffolds have not been summarized. Herein, a comprehensive presentation of the principles, preparation methods and application progress of animal-derived and plant-derived decellularized scaffolds has been reported in detail. Additionally, their application in the culture of skeletal muscle, fat and connective tissue, which constitute the main components of edible cultured meat, have also been generally discussed. We also illustrate the potential applications and prospects of decellularized scaffold materials in future foods. This review of cultured meat and decellularized scaffold biomaterials provides new insight and great potential research prospects in food application and cellular agriculture.

Adventitial injection of HA/SA hydrogel loaded with PLGA rapamycin nanoparticle inhibits neointimal hyperplasia in a rat aortic wire injury model

Neointimal hyperplasia is a persistent complication after vascular interventions, and it is also the leading cause of vascular graft restenosis and failure after arterial interventions, so novel treatment methods are needed to treat this complication. We hypothesized that adventitial injection of HA/SA hydrogel loaded with PLGA rapamycin nanoparticle (hydrogel-PLGA-rapamycin) could inhibit neointimal hyperplasia in a rat aortic wire injury model. The HA/SA hydrogel was fabricated by the interaction of hyaluronic acid (HA), sodium alginate (SA), and CaCO₃; and loaded with PLGA rapamycin nanoparticle or rhodamine uniformly. A SD rat aortic wire injury induced neointimal hyperplasia model was developed, the control group only received wire injury, the adventitial application group received 10 μL hydrogel-PLGA-rapamycin after wire injury, and the adventitial injection group received 10 μL hydrogel-PLGA-rapamycin injected into the aortic adventitia after wire injury. Tissues were harvested at day 21 and analyzed by histology and immunohistochemical staining. Hydrogel loaded with rhodamine can be successfully injected into the aortic adventitia and was encapsuled by the adventitia. The hydrogel could be seen beneath the adventitia after adventitial injection but was almost degraded at day 21. There was a significantly thinner neointima in the adventitial application group and adventitial injection group compared to the control group (p = 0.0009). There were also significantly fewer CD68⁺ (macrophages) cells (p = 0.0012), CD3⁺ (lymphocytes) cells (p = 0.0011), p-mTOR⁺ cells (p = 0.0019), PCNA⁺ cells (p = 0.0028) in the adventitial application and adventitial injection groups compared to the control group. The endothelial cells expressed arterial identity markers (Ephrin-B2 and dll-4) in all these three groups. Adventitial injection of hydrogel-PLGA-rapamycin can effectively inhibit neointimal hyperplasia after rat aortic wire injury. This may be a promising drug delivery method and therapeutic choice to inhibit neointimal hyperplasia after vascular interventions.

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.

Wood-Derived Vascular Patches Loaded With Rapamycin Inhibit Neointimal Hyperplasia

Background: Patches are commonly used to close blood vessels after vascular surgery. Most currently used materials are either prosthetics or animal-derived; although natural materials, such as a leaf, can be used as a patch, healing of these natural materials is not optimal; rhodamine and rapamycin have been used to show that coating patches with drugs allow drug delivery to inhibit neointimal hyperplasia that may improve patch healing. Wood is abundant, and its stiffness can be reduced with processing; however, whether wood can be used as a vascular patch is not established. We hypothesized that wood can be used as a vascular patch and thus may serve as a novel plant-based biocompatible material.

Method: Male Sprague–Dawley rats (aged 6–8 weeks) were used as an inferior vena cava (IVC) patch venoplasty model. After softening, wood patches coated with rhodamine and rapamycin were implanted into the rat subcutaneous tissue, the abdominal cavity, or the IVC. Samples were explanted on day 14 for analysis.

Result: Wood patches became soft after processing. Patches showed biocompatibility after implantation into the subcutaneous tissue or the abdominal cavity. After implantation into the IVC, the patches retained mechanical strength. There was a significantly thinner neointima in wood patches coated with rapamycin than control patches (146.7 ± 15.32 μm vs. 524.7 ± 26.81 μm; p = 0.0001). There were CD34 and nestin-positive cells throughout the patch, and neointimal endothelial cells were Eph-B4 and COUP-TFII-positive. There was a significantly smaller number of PCNA and α-actin dual-positive cells in the neointima (p = 0.0003), peri-patch area (p = 0.0198), and adventitia (p = 0.0004) in wood patches coated with rapamycin than control patches. Piezo1 was expressed in the neointima and peri-patch area, and there were decreased CD68 and piezo1 dual-positive cells in wood patches coated with rapamycin compared to control patches.

Conclusion: Wood can be used as a novel biomaterial that can be implanted as a vascular patch and also serve as a scaffold for drug delivery. Plant-derived materials may be an alternative to prosthetics or animal-based materials in vascular applications.

Chitosan-Heparin Polyelectrolyte Multilayer-Modified Poly(vinyl alcohol) Vascular Patches based on a Decellularized Scaffold for Vascular Regeneration

Vascular patches play an important role in vascular reparation and cardiovascular diseases therapy. Recently, decellularized scaffold (DCS)-based vascular patches have drawn attention for their good biocompatibility and blood compatibility. In this work, we developed a poly(vinyl alcohol)-coated DCS as a vascular patch for vascular regeneration. Polyelectrolyte multilayers (PEMs) were further decorated on the surface via layer-by-layer (LbL) self-assembly to improve the biocompatibility of the vascular patch. According to the in vitro experiment, the vascular patch exhibited rapid endothelialization and good hemocompatibility. Compared with unmodified poly(vinyl alcohol)/DCS, the PEM-modified vascular patch possesses improved hemocompatibility, for example, enhanced anti-platelet adhesion ability, prolonged in vitro coagulation time, and decreased hemolysis rate. Therefore, this vascular patch is conducive to the proliferation and attachment of endothelial progenitor cells. Meanwhile, the in vivo performance in a porcine model was investigated with the in vivo computed tomography angiography and B ultrasound was used to further confirm the vascular regeneration. Excitedly, the porcine artery could remain unblocked for 5 months after implantation. Our current research provides a potential strategy for treating diseased blood vessels in clinical surgery.

Recent Advances in Development of Natural Cellulosic Non-Woven Scaffolds for Tissue Engineering

In recent years, tissue engineering researchers have exploited a variety of biomaterials that can potentially mimic the extracellular matrix (ECM) for tissue regeneration. Natural cellulose, mainly obtained from bacterial (BC) and plant-based (PC) sources, can serve as a high-potential scaffold material for different regenerative purposes. Natural cellulose has drawn the attention of researchers due to its advantages over synthetic cellulose including its availability, cost effectiveness, perfusability, biocompatibility, negligible toxicity, mild immune response, and imitation of native tissues. In this article, we review recent in vivo and in vitro studies which aimed to assess the potential of natural cellulose for the purpose of soft (skin, heart, vein, nerve, etc.) and hard (bone and tooth) tissue engineering. Based on the current research progress report, it is sensible to conclude that this emerging field of study is yet to satisfy the clinical translation criteria, though reaching that level of application does not seem far-fetched.

Egg Shell Membrane as an Alternative Vascular Patch for Arterial Angioplasty

Introduction: The egg shell membrane (ESM) is always considered as waste, but recent studies have shown that it has the potential to yield rapid re-endothelialization in vitro. We hypothesized that ESM and heparin-conjugated ESM (HESM) can be used as arterial patch in a rat aortic angioplasty model.

Method: Sprague-Dawley rat (200 g) abdominal aortic patch angioplasty model was used. Decellularized rat thoracic aorta (TA) patch was used as the control; ESM patch was made of raw chicken egg; heparin-coated ESM (HESM) patch was made by using dopamine; anticoagulation properties were verified using platelet adhesion tests; the TA, ESM, and HESM patches were implanted to the rat aorta and harvested at day 14; and the samples were examined by immunohistochemistry and immunofluorescence.

Result: The ESM patch showed a similar healing process to the TA patch; the cells could migrate and infiltrate into both patches; there was a neointima with von Willebrand factor-positive endothelial cells; the endothelial cells acquired arterial identity with Ephrin-B2- and dll-4-positive cells; there were proliferating cell nuclear antigen (PCNA)-positive cells, and PCNA and alpha smooth muscle actin dual-positive cells in the neointima in both groups. Heparin was conjugated to the patch successfully and showed a strong anticoagulation property in vitro. HESM could decrease mural thrombus formation after rat aortic patch angioplasty.

Conclusion: The ESM is a natural scaffold that can be used as a vascular patch; it showed a similar healing process to decellularized TA patch; HESM showed anticoagulation property both in vitro and in vivo; and the ESM may be a promising vascular graft in the clinic.

PLGA Nanoparticle Rapamycin- or Necrostatin-1-Coated Sutures Inhibit Inflammatory Reactions after Arterial Closure in Rats

Background: The inflammatory reaction of sutures and oozing after arterial closure depends on the suture material and the amount of oozing surrounding the sutures. Anti-inflammation coatings have been proven to be an effective strategy to decrease this reaction. The aim of this study was to establish an arterial closure oozing model in rats and to test the effect of poly (lactic-co-glycolic acid) (PLGA) nanoparticle (NP) rapamycin- or necrostatin-1(NEC-1)-coated sutures on the inflammatory reaction after arterial closure. Methods and Materials: A 10 mm arteriotomy was carried out on the carotid artery of Sprague-Dawley rats and closed using 11-0 sutures. PLGA NP-rapamycin and NEC-1 were made. The 11/0 nylon sutures were coated with PLGA NP-rapamycin and NEC-1. Sutures were examined by scanning electron microscopy, hemolysis test, and cumulative release. The carotid arteriotomy was closed using uncoated PLGA NP-rapamycin- and NP-NEC-1-coated sutures. The carotid artery was harvested on day 7. Tissues were examined by histology and immunohistochemistry. Results: There were severe inflammatory reactions in the oozing arteries compared to the normal healing arteries (P = 0.0192). PLGA NP-rapamycin- and NEC -1-coated sutures reduced foreign body reaction compared to the uncoated sutures. There were significantly smaller number of CD3 (P = 0.0068), CD45 (P = 0.0300), and CD68 (P = 0.0011) cells in the PLGA NP-rapamycin- and NP-NEC-1-coated groups compared to the uncoated group. There was a smaller number of p-mTOR (P = 0.0198)-positive cells in the PLGA NP-rapamycin-coated group compared to the uncoated group. There was a smaller number of TNFα (P = 0.0198)-positive cells in the PLGA NP-NEC-1-coated group compared to the uncoated group. Conclusions: In this rat carotid artery oozing model, PLGA NP-rapamycin- or NP-NEC-1-coated sutures can inhibit inflammatory reaction and foreign body reaction. Although this was a small rodent animal experiment, this coated suture may have a potential clinical application in the future.

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.

Decellularized Scaffold-based Poly(ethylene glycol) Biomimetic Vascular Patches Modified with Polyelectrolyte Multilayer of Heparin and Chitosan: Preparation and Vascular Tissue Engineering Applications in a Porcine Model

The mechanical property mismatch between vascular patches and native blood vessels can result in post-operation failure, so it is important to develop vascular patches that mimic the biomechanical properties of...

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.

The Emerging Role of Decellularized Plant-Based Scaffolds as a New Biomaterial

The decellularization of plant-based biomaterials to generate tissue-engineered substitutes or in vitro cellular models has significantly increased in recent years. These vegetal tissues can be sourced from plant leaves and stems or fruits and vegetables, making them a low-cost, accessible, and sustainable resource from which to generate three-dimensional scaffolds. Each construct is distinct, representing a wide range of architectural and mechanical properties as well as innate vasculature networks. Based on the rapid rise in interest, this review aims to detail the current state of the art and presents the future challenges and perspectives of these unique biomaterials. First, we consider the different existing decellularization techniques, including chemical, detergent-free, enzymatic, and supercritical fluid approaches that are used to generate such scaffolds and examine how these protocols can be selected based on plant cellularity. We next examine strategies for cell seeding onto the plant-derived constructs and the importance of the different functionalization methods used to assist in cell adhesion and promote cell viability. Finally, we discuss how their structural features, such as inherent vasculature, porosity, morphology, and mechanical properties (i.e., stiffness, elasticity, etc.) position plant-based scaffolds as a unique biomaterial and drive their use for specific downstream applications. The main challenges in the field are presented throughout the discussion, and future directions are proposed to help improve the development and use of vegetal constructs in biomedical research.

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.