Microvessels derived from hiPSCs are a novel source for angiogenesis and tissue regeneration

Vascular and immune interactions in islets transplantation and 3D islet models

The aim of regenerative medicine is to restore specific functions to damaged cells or tissues. A crucial aspect of success lies in effectively reintegrating these cells or tissues within the recipient organism. This is particularly pertinent for diabetes, where islet function relies on the close connection of beta cells to the bloodstream for glucose sensing and insulin release. Central to this approach is the need to establish a fast connection with the host's vascular system. In this review, we explore the intricate relationships between endocrine, vascular, and immune cell interactions in transplantation outcomes. We also delve into recent strategies aimed at enhancing engraftment, along with the utilization of in vitro platforms to model cellular interactions.

Injectable Microparticle-containing hydrogel with controlled release of bioactive molecules for facial rejuvenation

The skin is the largest organ and a crucial barrier for protection against various intrinsic and extrinsic factors. As we age, the skin's components become more vulnerable to damage, forming wrinkles. Among different procedures, hyaluronic acid-based hydrogel has been extensively utilized for skin regeneration and reducing wrinkles. However, it has limitations like low retention and weak mechanical properties. In this study, we suggested the poly(l-lactic acid) (PLLA) microparticles containing alkaline magnesium hydroxide and nitric oxide-generating zinc oxide and rejuvenative hyaluronic acid (HA) hydrogels including these functional microparticles and asiaticoside, creating a novel delivery system for skin rejuvenation and regeneration. The fabricated rejuvenative hydrogels have exhibited enhanced biocompatibility, pH neutralization, reactive oxygen species scavenging, collagen biosynthesis, and angiogenesis capabilities in vitro and in vivo. Additionally, an excellent volume retention ability was demonstrated due to the numerous hydrogen bonds that formed between hyaluronic acid and asiaticoside. Overall, our advanced injectable hydrogel containing functional microparticles, with controlled release of bioactive molecules, has a significant potential for enhancing the regeneration and rejuvenation of the skin.

Bulk Modification with Inorganic Particles and Immobilization of Extracellular Vesicles onto PDO Composite for Facial Rejuvenation

BACKGROUND

The skin, a vital organ protecting against microorganisms and dehydration, undergoes structural decline with aging, leading to visible issues such as wrinkles and sagging. Reduced blood vessels exacerbate vulnerability, hindering optimal cellular function and compromising skin health. Polydioxanone (PDO) biomaterials address aging concerns but produce acidic byproducts, causing inflammation. Inorganic particles and nitric oxide (NO) play crucial roles in inhibiting inflammation and promoting skin regeneration. Stem cell-derived extracellular vesicles (EVs) contribute to intercellular communication, offering the potential to enhance cell functions. The study proposes a method to enhance PDO-based medical devices by incorporating inorganic particles and immobilizing EVs, focusing on facial rejuvenation, anti-inflammatory response, collagen formation, and angiogenesis.

METHOD

PDO composites with inorganic particles such as magnesium hydroxide (MH) and zinc oxide (ZO) were prepared and followed by EV immobilization. Comprehensive characterization included biocompatibility, anti-inflammation, collagen formation ability, and angiogenesis ability.

RESULTS

Bulk-modified PDO composites demonstrated even dispersion of inorganic particles, pH neutralization, and enhanced biocompatibility. EVs immobilized on the composite surface exhibited spherical morphology. Inflammation-related gene expressions decreased, emphasizing anti-inflammatory effects. Collagen-related gene and protein expressions increased, showcasing collagen formation ability. In addition, angiogenic capabilities were notably improved, indicating potential for skin rejuvenation.

CONCLUSION

The study successfully developed and characterized PDO composites with inorganic particles and EVs, demonstrating promising attributes for medical applications. These composites exhibit biocompatibility, anti-inflammatory properties, collagen formation ability, and angiogenic potential, suggesting their utility in skin rejuvenation and tissue engineering. Further research and clinical validation are essential.

Double hits with bioactive nanozyme based on cobalt-doped nanoglass for acute and diabetic wound therapies through anti-inflammatory and pro-angiogenic functions

Regeneration of pathological wounds, such as diabetic ulcers, poses a significant challenge in clinical settings, despite the widespread use of drugs. To overcome clinical side effects and complications, drug-free therapeutics need to be developed to promote angiogenesis while overcoming inflammation to restore regenerative events. This study presents a novel bioactive nanozyme based on cobalt-doped nanoglass (namely, CoNZ), which exhibits high enzymatic/catalytic activity while releasing therapeutic ions. Cobalt oxide "Co3O4" tiny crystallites produced in situ through a chemical reaction with H2O2 within CoNZ nanoparticles play a crucial role in scavenging ROS. Results showed that CoNZ-treatment to full-thickness skin wounds in mice significantly accelerated the healing process, promoting neovascularization, matrix deposition, and epithelial lining while reducing pro-inflammatory signs. Notably, CoNZ was highly effective in treating pathological wounds (streptozotocin-induced diabetic wounds). Rapid scavenging of ROS by CoNZ and down-regulation of pro-inflammatory markers while up-regulating tissue healing signs with proliferative cells and activated angiogenic factors contributed to the observed healing events. In vitro experiments involving CoNZ-cultures with macrophages and endothelial cells exposed to high glucose and ROS-generating conditions further confirmed the effectiveness of CoNZ. CoNZ-promoted angiogenesis was attributed to the release of cobalt ions, as evidenced by the comparable effects of CoNZ-extracted ionic medium in enhancing endothelial migration and tubule formation via activated HIF-1α. Finally, we compared the in vivo efficacy of CoNZ with the clinically-available drug deferoxamine. Results demonstrated that CoNZ was as effective as the drug in closing the diabetic wound, indicating the potential of CoNZ as a novel drug-free therapeutic approach.

Recent advances in tissue repair of the blood-brain barrier after stroke

The selective permeability of the blood-brain barrier (BBB) enables the necessary exchange of substances between the brain parenchyma and circulating blood and is important for the normal functioning of the central nervous system. Ischemic stroke inflicts damage upon the BBB, triggering adverse stroke outcomes such as cerebral edema, hemorrhagic transformation, and aggravated neuroinflammation. Therefore, effective repair of the damaged BBB after stroke and neovascularization that allows for the unique selective transfer of substances from the BBB after stroke is necessary and important for the recovery of brain function. This review focuses on four important therapies that have effects of BBB tissue repair after stroke in the last seven years. Most of these new therapies show increased expression of BBB tight-junction proteins, and some show beneficial results in terms of enhanced pericyte coverage at the injured vessels. This review also briefly outlines three effective classes of approaches and their mechanisms for promoting neoangiogenesis following a stroke.

Emerging strategies for tissue engineering in vascularized composite allotransplantation: A review

Vascularized composite allotransplantation (VCA), which can effectively improve quality of life, is a promising therapy for repair and reconstruction after face or body trauma. However, intractable issues are associated with VCA, such as the inevitable multiple immunogenicities of different tissues that cause severe rejection, the limited protocols available for clinical application, and the shortage of donor sources. The existing regimens used to extend the survival of patients receiving VCAs and suppress rejection are generally the lifelong application of immunosuppressive drugs, which have side effects. Consequently, studies aiming at tissue engineering methods for VCA have become a topic. In this review, we summarize the emerging therapeutic strategies for tissue engineering aimed to prolong the survival time of VCA grafts, delay the rejection and promote prevascularization and tissue regeneration to provide new ideas for future research on VCA treatment.

Core-Shell Droplet-Based Angiogenic Patches for the Treatment of Ischemic Diseases: Ultrafast Processability, Physical Tunability, and Controlled Delivery of an Angiogenic Cocktail

The patch-based delivery system has been a promising therapeutic approach for treating various vascular diseases. However, conventional methods face several challenges, including labor-intensive and time-consuming processes associated with patch fabrication or factor incorporation, inadequate physical properties, and uncontrolled release of factors. These limitations restrict the potential applications in clinical settings. To overcome these issues, we propose a novel core-shell-shaped droplet patch system called an angiogenic patch (AP). Our system offers several distinct advantages over conventional patches. It enables a rapid and straightforward fabrication process utilizing only two biodegradable ingredients [alginate and ε-poly(l-lysine)], ensuring minimal toxicity. Moreover, the AP exhibits excellent physical integrity to match and withstand physiological mechanics and allows for customizable patch dimensions tailored to individual patients' pathological conditions. Notably, the AP enables facile loading of angiogenic cytokines during patch fabrication, allowing sustained release at a controlled rate through tunable network cross-linking. Subsequently, the AP, delivering a precisely formulated cocktail of angiogenic cytokines (VEGF, bFGF, EGF, and IGF), demonstrated significant effects on endothelial cell functions (migration and tubule formation) and survival under pathological conditions simulating ischemic injury. Likewise, in in vivo experiments using a mouse model of hindlimb ischemia, the AP encapsulating the angiogenic cocktail effectively restored blood flow following an ischemic insult, promoting muscle regeneration and preventing limb loss. With its simplicity and rapid processability, user-friendly applicability, physical tunability, and the ability to efficiently load and control the delivery of angiogenic factors, the AP holds great promise as a therapeutic means for treating patients with ischemic diseases.

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Promoting angiogenesis and diabetic wound healing through delivery of protein transduction domain-BMP2 formulated nanoparticles with hydrogel

Decreased angiogenesis contributes to delayed wound healing in diabetic patients. Recombinant human bone morphogenetic protein-2 (rhBMP2) has also been demonstrated to promote angiogenesis. However, the short half-lives of soluble growth factors, including rhBMP2, limit their use in wound-healing applications. To address this limitation, we propose a novel delivery model using a protein transduction domain (PTD) formulated in a lipid nanoparticle (LNP). We aimed to determine whether a gelatin hydrogel dressing loaded with LNP-formulated PTD-BMP2 (LNP-PTD-BMP2) could enhance the angiogenic function of BMP2 and improve diabetic wound healing. In vitro, compared to the control and rhBMP2, LNP-PTD-BMP2 induced greater tube formation in human umbilical vein endothelial cells and increased the cell recruitment capacity of HaCaT cells. We inflicted large, full-thickness back skin wounds on streptozotocin-induced diabetic mice and applied gelatin hydrogel (GH) cross-linked by microbial transglutaminase containing rhBMP2, LNP-PTD-BMP2, or a control to these wounds. Wounds treated with LNP-PTD-BMP2-loaded GH exhibited enhanced wound closure, increased re-epithelialization rates, and higher collagen deposition than those with other treatments. Moreover, LNP-PTD-BMP2-loaded GH treatment resulted in more CD31- and α-SMA-positive cells, indicating greater neovascularization capacity than rhBMP2-loaded GH or GH treatments alone. Furthermore, in vivo near-infrared fluorescence revealed that LNP-PTD-BMP2 has a longer half-life than rhBMP2 and that BMP2 localizes around wounds. In conclusion, LNP-PTD-BMP2-loaded GH is a viable treatment option for diabetic wounds.