A Review of Type 1 and Type 2 Intraductal Papillary Neoplasms of the Bile Duct

Intraductal papillary neoplasm of the bile duct(IPNB)is a heterogeneous disease similar to intraductal papillary mucinous neoplasm of the pancreas.These lesions have been recognized as one of the three major precancerous lesions in the biliary tract since 2010.In 2018,Japanese and Korean pathologists reached a consensus,classifying IPNBs into type l and type 2 IPNBs.IPNBs are more prevalent in male patients in East Asia and are closely related to diseases such as cholelithiasis and schistosomiasis.From a molecular genetic perspective,IPNBs exhibit early genetic variations,and different molecular pathways may be involved in the tumorigenesis of type 1 and type 2 IPNBs.The histological subtypes of IPNBs include gastric,intestinal,pancreaticobiliary,or oncocytic subtypes,but type 1 IPNBs typically exhibit more regular and well-organized histological features than type 2 IPNBs and are more commonly found in the intrahepatic bile ducts with abundant mucin.Due to the rarity of these lesions and the absence of specific clinical and laboratory features,imaging is crucial for the preoperative diagnosis of IPNB,with local bile duct dilation and growth along the bile ducts being the main imaging features.Surgical resection remains the optimal treatment for IPNBs,but negative bile duct margins and the removal of lymph nodes in the hepatic hilum significantly improve the postoperative survival rates for patients with IPNBs.

Prevascularized Micro‑/Nano‑Sized Spheroid/Bead Aggregates for Vascular Tissue Engineering

Efficient strategies to promote microvascularization in vascular tissue engineering,a central priority in regenerative medicine,are still scarce;nano-and micro-sized aggregates and spheres or beads harboring primitive microvascular beds are promising methods in vascular tissue engineering.Capillaries are the smallest type and in numerous blood vessels,which are distributed densely in cardiovascular system.To mimic this microvascular network,specific cell components and proangiogenic factors are required.Herein,advanced biofabrication methods in microvascular engineering,including extrusion-based and droplet-based bioprinting,Kenzan,and biogripper approaches,are deliberated with emphasis on the newest works in prevascular nano-and micro-sized aggregates and microspheres/microbeads.

Protective effect of tannins from Ficus racemosa in hypercholesterolemia and diabetes induced vascular tissue damage in rats

Objective:To evaluate the protective effect of tannins from Ficus racemosa(F.racemosa) on the lipid profile and antioxidant parameters in high fat meal and streptozotocin induced hypercholestremia associated diabetes model in rats.Methods:The crude tannin fraction was separated from the acetone(70%v/v) bark extract of F.racemosa.Oral administratipn of tannin fraction(TF)(100 & 200 mg/kg body weight) to rats fed with high fat meal for 30 days (4%cholesterol,1%cholic acid,0.5%egg albumin) and injected with streptozotocin(35 mg/ kg i.p.in citrate buffer on 14th day).Results:The administration of TF significantly reverse the increased blood glucose,total cholesterol,triglycerides,low density lipoprotein and also significandy restored the insulin and high density lipoprotein in the serum.In addition tannins significantly restored the activity of antioxidant enzymes such as superoxide dismutase,catalase and decreased the,glutathione peroxidase,and glutathione,thereby restoring the antioxidant status of the organs to almost normal levels.Conclutions:The results of this study show that two different doses of tannin supplementation had a favorable effect on plasma glucose and lipid profile concentrations.It also had an influence on attenuating oxidative stress in diabetic tats.

Fabrication of a Bi-layer Tubular Scaffold Consisted of a Dense Nanofibrous Inner Layer and a Porous Nanoyarn Outer Layer for Vascular Tissue Engineering

Recent years, it has attracted more attentions to increase the porosity and pore size of nanofibrous scaffolds to provide the for the cells to grow into the small-diameter vascular grafts. In this study, a novel bi-layer tubular scaffold with an inner layer and an outer layer was fabricated. The inner layer was random collagen/poly （ L-lactide-co-caprolactone ） I P （ LLA- CL） ] nanofibrous mat fabricated by conventional electrospinning and the outer layer was aligned collagen/P （LLA-CL） nanoyarns prepared by a dynamic liquid dectrospinning method. Fourier transform infrared spectroscopy （FTIR） was used to characterize the chemical structure. Scanning electron microscopy （ SEM ） was employed to observe the morphology of the layers and the cross- sectioned bi-layer tubular scaffold. A liquid displacement method was employed to measure the porosities of the inner and outer layers. Stress-strain curves were obtained to evaluate the mechanical properties of the two different layers and the bi-layer membrane. The diameters of the nanofibers and the nanoyarns were （480 ± 197 ） nm and （ 19.66 ± 4.05 ） μm, respectively. The outer layer had a significantly higher porosity and a larger pore size than those of the inner layer. Furthermore, the bi-layer membrane showed a good mechanical property which was suitable as small-diameter vascular graft. The results indicated that the bi-layer tubular scaffold had a great potential application in small vascular tissue engineering.

Gibberellin promotes cambium reestablishment during secondary vascular tissue regeneration after girdling in an auxin-dependent manner in Populus

Secondary vascular tissue(SVT)development and regeneration are regulated by phytohormones.In this study,we used an in vitro SVT regeneration system to demonstrate that gibberellin(GA)treatment significantly promotes auxin-induced cambium reestablishment.Altering GA content by overexpressing or knocking down ent-kaurene synthase(KS)affected secondary growth and SVT regeneration in poplar.The poplar DELLA gene GIBBERELLIC ACID INSENSITIVE(PtoGAI)is expressed in a specific pattern during secondary growth and cambium regeneration after girdling.Overexpression of PtoGAI disrupted poplar growth and inhibited cambium regeneration,and the inhibition of cambium regeneration could be partially restored by GA application.Further analysis of the PtaDR5:GUS transgenic plants,the localization of PIN-FORMED 1(PIN1)and the expression of auxin-related genes found that an additional GA treatment could enhance the auxin response as well as the expression of PIN1,which mediates auxin transport during SVT regeneration.Taken together,these findings suggest that GA promotes cambium regeneration by stimulating auxin signal transduction.

Diagnosis, treatment, and current concepts in the endoscopic management of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms(GEP-NENs)are rare tumors derived from the neuroendocrine cell system,which that have increased in incidence and prevalence in recent years.Despite improvements in radiological and metabolic imaging,endoscopy still plays a pivotal role in the number of GEPNENs.Tumor detection,characterization,and staging are essential in management and treatment planning.Upper and lower gastrointestinal(GI)endoscopy is essential for correct localization of the primary tumor site of GI NENs.Endoscopic ultrasonography(EUS)has an important role in the imaging and tissue acquisition of pancreatic NENs and locoregional staging of GI neuroendocrine tumors.Correct staging and histological diagnosis have important prognostic implications.Endoscopic operating techniques allow the removal of small GI NENs in the early stage of mucosal or submucosal invasion of the intestinal wall.Preoperative EUS-guided techniques may help the surgeon locate small and deep tumors,thus avoiding formal pancreatic resections in favor of parenchymal-sparing surgery.Finally,locoregional ablative treatments have been proposed in recent studies with promising results in selected patients.

Engineering vascularized organotypic tissues via module assembly

Adequate vascularization is a critical determinant for the successful construction and clinical implementation of complex organotypic tissue models. Currently, low cell and vessel density and insufficient vascular maturation make vascularized organotypic tissue construction difficult,greatly limiting its use in tissue engineering and regenerative medicine. To address these limitations, recent studies have adopted pre-vascularized microtissue assembly for the rapid generation of functional tissue analogs with dense vascular networks and high cell density. In this article, we summarize the development of module assembly-based vascularized organotypic tissue construction and its application in tissue repair and regeneration, organ-scale tissue biomanufacturing, as well as advanced tissue modeling.

Vascular endothelial growth factor/connective tissue growth factor and proteomic analysis of aqueous humor after intravitreal conbercept for proliferative diabetes retinopathy

AIM:To investigate the role of connective tissue growth factor(CTGF)and vascular endothelial growth factor(VEGF)in the protein profile of the aqueous humor in patients with proliferative diabetic retinopathy(PDR)following intravitreal injection of conbercept.METHODS:This study included 72 PDR patients and 8 cataract patients as controls.PDR patients were divided into 3 groups according to the intervals of 3,5,and 7d between intravitreal conbercept(IVC,0.5 mg/0.05 mL)injection and pars plana vitrectomy(PPV)performed.Aqueous humor samples were collected before and after IVC and PPV for VEGF and CTGF levels detected with enzyme-linked immunosorbent assay(ELISA).The differential proteomics of 10 patients who underwent PPV surgery 5d after IVC and 8 normal controls was studied,Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis were performed on the data,and the protein interaction network of 23 differential proteins was studied.RESULTS:Post-IVC,VEGF levels decreased and CTGF levels increased significantly in aqueous humor,with the CTGF/VEGF ratio rising significantly at all intervals.Liquid chromatography tandem mass spectrometry(LC-MS/MS)identified differentially expressed proteins between preand post-IVC samples.GO and KEGG analyses revealed involvement in immune response,stress response,complement and coagulation cascades,ferroptosis,and PPAR signaling pathways.PPI analysis highlighted key proteins like APOA1,C3,and transferrin(TF).ELISA assay confirmed the differential expression of proteins such as HBA1,SERPINA1,COL1A1,and ACTB,with significant changes in the IVC groups.CONCLUSION:The study demonstrates that IVC effectively reduces VEGF levels while increasing CTGF levels,thereby modifying the CTGF/VEGF ratio,and IVC significantly alters the protein profile in the aqueous humor of patients with PDR.Proteomic analysis reveals that these changes are associated with critical biological pathways and protein interactions involved in immune response,stress response,and cellular metabolism.

High-resolution anatomical and spatial transcriptome analyses reveal two types of meristematic cell pools within the secondary vascular tissue of poplar stem

The secondary vascular tissue emanating from meristems is central to understanding how vascular plants such as forest trees evolve,grow,and regulate secondary radial growth.However,the overall molecular characterization of meristem origins and developmental trajectories from primary to secondary vascular tissues in woody tree stems is technically challenging.In this study,we combined high-resolution anatomic analysis with a spatial transcriptome(ST)technique to define features of meristematic cells in a developmental gradient from primary to secondary vascular tissues in poplar stems.The tissue-specific gene expression of meristems and derived vascular tissue types were accordingly mapped to specific anatomical domains.Pseudotime analyses were used to track the origins and changes of meristems throughout the development from primary to secondary vascular tissues.Surprisingly,two types of meristematic-like cell pools within secondary vascular tissues were inferred based on high-resolution microscopy combined with ST,and the results were confirmed by in situ hybridization of,transgenic trees,and single-cell sequencing.The rectangle shape procambium-like(PCL)cells develop from procambium meristematic cells and are located within the phloem domain to produce phloem cells,whereas fusiform shape cambium zone(CZ)meristematic cells develop from fusiform metacambium meristematic cells and are located inside the CZ to produce xylem cells.The gene expression atlas and transcriptional networks spanning the primary transition to secondary vascular tissues generated in this work provide new resources for studying the regulation of meristem activities and the evolution of vascular plants.A web server(https://pgx.zju.edu.cn/stRNAPal/)was also established to facilitate the use of ST RNA-seq data.

Intelligent Vascularized 3D/4D/5D/6D‑Printed Tissue Scaffolds

Blood vessels are essential for nutrient and oxygen delivery and waste removal.Scaffold-repairing materials with functional vascular networks are widely used in bone tissue engineering.Additive manufacturing is a manufacturing technology that creates three-dimensional solids by stacking substances layer by layer,mainly including but not limited to 3D printing,but also 4D printing,5D printing and 6D printing.It can be effectively combined with vascularization to meet the needs of vascularized tissue scaffolds by precisely tuning the mechanical structure and biological properties of smart vascular scaffolds.Herein,the development of neovascularization to vascularization to bone tissue engineering is systematically discussed in terms of the importance of vascularization to the tissue.Additionally,the research progress and future prospects of vascularized 3D printed scaffold materials are highlighted and presented in four categories:functional vascularized 3D printed scaffolds,cell-based vascularized 3D printed scaffolds,vascularized 3D printed scaffolds loaded with specific carriers and bionic vascularized 3D printed scaffolds.Finally,a brief review of vascularized additive manufacturing-tissue scaffolds in related tissues such as the vascular tissue engineering,cardiovascular system,skeletal muscle,soft tissue and a discussion of the challenges and development efforts leading to significant advances in intelligent vascularized tissue regeneration is presented.

Efficacy of stromal vascular fraction for knee osteoarthritis:A prospective,single-centre,non-randomized study with 2 years follow-up

BACKGROUND Current osteoarthritis(OA)treatments focus on symptom relief without addressing the underlying disease process.In regenerative medicine,current treatments have limitations.In regenerative medicine,more research is needed for intra-articular stromal vascular fraction(SVF)injections in OA,including dosage optimization,long-term efficacy,safety,comparisons with other treatments,and mechanism exploration.AIM To compare the efficacy of intra-articular SVF with corticosteroid(ICS)injections in patients with primary knee OA.METHODS The study included 50 patients with Kellgren-Lawrence grades II and III OA.Patients were randomly assigned(1:1)to receive either a single intra-articular SVF injection(group A)or a single intra-articular ICS(triamcinolone)(group B)injection.Patients were followed up at 1,3,6,12,and 24 months.Visual analog score(VAS)and International Knee Documentation Committee(IKDC)scores were administered before the procedure and at all followups.The safety of SVF in terms of adverse and severe adverse events was recorded.Statistical analysis was performed with SPSS Version 26.0,IBM Corp,Chicago,IL,United States.RESULTS Both groups had similar demographics and baseline clinical characteristics.Follow-up showed minor patient loss,resulting in 23 and 24 in groups A and B respectively.Group A experienced a notable reduction in pain,with VAS scores decreasing from 7.7 to 2.4 over 24 months,compared to a minor reduction from 7.8 to 6.2 in Group B.This difference in pain reduction in group A was statistically significant from the third month onwards.Additionally,Group A showed significant improvements in knee functionality,with IKDC scores rising from 33.4 to 83.10,whereas Group B saw a modest increase from 36.7 to 45.16.The improvement in Group A was statistically significant from 6 months and maintained through 24 months.CONCLUSION Our study demonstrated that intra-articular administration of SVF can lead to reduced pain and improved knee function in patients with primary knee OA.More adequately powered,multi-center,double-blinded,randomised clinical trials with longer follow-ups are needed to further establish safety and justify its clinical use.

In situ forming injectable MSC-loaded GelMA hydrogels combined with PD for vascularized sweat gland regeneration

Dear Editor,Three dimensional(3D)bioprinted extracellular matrix(ECM)can be used to provide both biochemical and biophysical cues to direct mesenchymal stem cells(MSCs)differentiation,and then differentiated cells were isolated for implantation in vivo using surgical procedures.However,the reduced cell activity after cell isolation from 3D constructs and low cell retention in injured sites limit its application[1].Methacrylated gelatin(GelMA)hydrogel has the advantage of fast crosslinking,which could resemble complex architectures of tissue construct in vivo[2].Here,we adopted a noninvasive bioprinting procedure to imitate the regenerative microenvironment that could simultaneously direct the sweat gland(SG)and vascular differentiation from MSCs and ultimately promote the replacement of glandular tissue in situ(Fig.1a).

Understanding and controlling the variables for stromal vascular fraction therapy

In regenerative medicine,the isolation of mesenchymal stromal cells(MSCs)from the adipose tissue’s stromal vascular fraction(SVF)is a critical area of study.Our review meticulously examines the isolation process of MSCs,starting with the extraction of adipose tissue.The choice of liposuction technique,anatomical site,and immediate processing are essential to maintain cell functionality.We delve into the intricacies of enzymatic digestion,emphasizing the fine-tuning of enzyme concentrations to maximize cell yield while preventing harm.The review then outlines the filtration and centrifugation techniques necessary for isolating a purified SVF,alongside cell viability assessments like flow cytometry,which are vital for confirming the efficacy of the isolated MSCs.We discuss the advantages and drawbacks of using autologous vs allogeneic SVF sources,touching upon immunocompatibility and logistical considerations,as well as the variability inherent in donor-derived cells.Anesthesia choices,the selection between hypo-dermic needles vs liposuction cannulas,and the role of adipose tissue lysers in achieving cellular dissociation are evaluated for their impact on SVF isolation.Centrifugation protocols are also analyzed for their part in ensuring the integrity of the SVF.The necessity for standardized MSC isolation protocols is highlighted,promoting reproducibility and successful clinical application.We encourage ongoing research to deepen the understanding of MSC biology and therapeutic action,aiming to further the field of regenerative medicine.The review concludes with a call for rigorous research,interdisciplinary collaboration,and strict adherence to ethical and regulatory standards to safeguard patient safety and optimize treatment outcomes with MSCs.

Advances in the differentiation of pluripotent stem cells into vascular cells

Blood vessels constitute a closed pipe system distributed throughout the body,transporting blood from the heart to other organs and delivering metabolic waste products back to the lungs and kidneys.Changes in blood vessels are related to many disorders like stroke,myocardial infarction,aneurysm,and diabetes,which are important causes of death worldwide.Translational research for new appro-aches to disease modeling and effective treatment is needed due to the huge socio-economic burden on healthcare systems.Although mice or rats have been widely used,applying data from animal studies to human-specific vascular physiology and pathology is difficult.The rise of induced pluripotent stem cells(iPSCs)provides a reliable in vitro resource for disease modeling,regenerative medicine,and drug discovery because they carry all human genetic information and have the ability to directionally differentiate into any type of human cells.This review summarizes the latest progress from the establishment of iPSCs,the strategies for differentiating iPSCs into vascular cells,and the in vivo trans-plantation of these vascular derivatives.It also introduces the application of these technologies in disease modeling,drug screening,and regenerative medicine.Additionally,the application of high-tech tools,such as omics analysis and high-throughput sequencing,in this field is reviewed.

Increased expressions of vascular endothelial growth factor(VEGF),VEGF-C and VEGF receptor-3 in prostate cancer tissue are associated with tumor progression

Aim： To investigate the differences in microvessel densities （MVD） and the expressions of vascular endothelial growth factor （VEGF）, VEGF-C and VEGF receptor-3 （VEGFR-3） between prostate cancer （PCa） tissues and adjacent benign tissues, and to explore the correlations among MVD, Jewett-Whitmore staging, Gleason scores and expressions of VEGF, VEGF-C and VEGFR-3 in the progression of PCa. Methods： An immunohistochemical approach was adopted to detect the expressions of CD34, VEGF, VEGF-C and VEGFR-3 in both cancer areas and peripheral benign areas of 71 primary prostatic adenocarcinoma specimens. A statistic analysis was then performed according to the experimental and clinic data. Results： Significantly upregulated expressions of VEGF, VEGF-C and VEGFR-3 were all found in malignant epithelium/cancer cells compared with adjacent benign epithelium （P 〈 0.01）. Patients in stage D had a significantly higher score than patients in stage A, B or C when comparing the expression of VEGF-C or VEGFR-3 in the tumor area （P 〈 0.01）. In addition, significant correlations were observed between Jewett-Whitmore staging and VEGF-C （rs = 0.738, P 〈 0.01）, clinical staging and VEGFR-3 （rs = 0.410, P 〈 0.01）, VEGF-C and Gleason scores （rs = 0.401, P 〈 0.01）, VEGFR-3 and Gleason scores （rs = 0.581, P 〈 0.001） and MVD and VEGF （rs = 0.492, P 〈 0.001）. Conclusion： Increased expressions of VEGF and VEGF-C were closely associ- ated with progression of PCa. The main contribution of increased VEGF expression for PCa progression was to upregulate MVD, which maintained the growth advantage of tumor tissue. However, the chief role of increased expressions of VEGF-C and VEGFR-3 was to enhance lymphangiogenesis and provide a main pathway for cancer cells to disseminate. （Asian J Androl 2006 Mar; 8： 169-175）

Homocysteine-induced Enhanced Expression of Tissue Factor in Human Vascular Smooth Muscle Cells

The homocysteine （Hcy）-induced tissue factor （TF） expression in human vascular smooth muscle cells （VSMCs） and the effect of Hcy on the activity of nuclear factor-kappaB （NF-кB） and the expression of inducible nitric oxide synthase （iNOS） were investigated. Human umbilical artery VSMCs were cultured by tissue explanting method, identified by α-actin immunohistochemistry, and incubated with different concentrations of Hcy/PTDC （NF-кB inhibitor）. Semi-quantitative RT-PCR was performed to detect the expression of TF mRNA in VSMCs. Flow cytometry was used to assay the expression of TF protein on the surface of VSMCs and the expression of iNOS in VSMCs. Western blot was carried out to detect the expression of NF-кB protein in nuclei. The results showed that Hcy could induce VSMCs expressing TF mRNA significantly after the VSMCs were incubated with Hcy at concentrations of 10, 100, 500 μmol/L respectively. There was low expression level of TF protein on the surface of the resting VSMCs and Hcy could also induce VSMCs expressing TF pro- tein on the cell surface in different concentrations. Additionally, Hcy could rapidly induce the activation of NF-кB and this effect could be significantly inhibited by PDTC. Hcy alone could not induce the expression of iNOS in VSMCs. It was concluded that Hcy could significantly induce the expression of TF in VSMCs and enhance the activation of NF-ΚB, subsequently mediate TF gene expression and protein synthesis. NF-кB-mediated expression of TF in VSMCs might be the important mechanism of atherosclerosis and thrombosis induced by Hcy.

3D printing of tissue engineering scaffolds:a focus on vascular regeneration

Tissue engineering is an emerging means for resolving the problems of tissue repair and organ replacement in regenerative medicine.Insufficient supply of nutrients and oxygen to cells in large-scale tissues has led to the demand to prepare blood vessels.Scaffold-based tissue engineering approaches are effective methods to form new blood vessel tissues.The demand for blood vessels prompts systematic research on fabrication strategies of vascular scaffolds for tissue engineering.Recent advances in 3D printing have facilitated fabrication of vascular scaffolds,contributing to broad prospects for tissue vascularization.This review presents state of the art on modeling methods,print materials and preparation processes for fabrication of vascular scaffolds,and discusses the advantages and application fields of each method.Specially,significance and importance of scaffold-based tissue engineering for vascular regeneration are emphasized.Print materials and preparation processes are discussed in detail.And a focus is placed on preparation processes based on 3D printing technologies and traditional manufacturing technologies including casting,electrospinning,and Lego-like construction.And related studies are exemplified.Transformation of vascular scaffolds to clinical application is discussed.Also,four trends of 3D printing of tissue engineering vascular scaffolds are presented,including machine learning,near-infrared photopolymerization,4D printing,and combination of self-assembly and 3D printing-based methods.

A fusion protein containing murine vascular endothelial growth factor and tissue factor induces thrombogenesis and suppression of tumor growth in a colon carcinoma model

Induction of tumor vasculature occlusion by targeting a thrombogen to newly formed blood vessels in tumor tissues represents an intriguing approach to the eradication of primary solid tumors. In the current study, we construct and express a fusion protein containing vascular endothelial growth factor (VEGF) and tissue factor (TF) to explore whether this fusion protein has the capability of inhibiting tumor growth in a colon carcinoma model. The murine cDNA of VEGF A and TF were amplified by reverse transcriptase polymerase chain reaction (RT-PCR), and then cloned into prokaryotic expression plasmid pQE30 with a linker. The expression product recombinant VEGF-TF (rVEGF-TF) was purified and proved to have comparable enzyme activity to a commercial TF and the capability of specific binding to tumor vessels. Significant decrease of tumor growth was found in the mice administered with rVEGF-TF on Day 6 after initiated rVEGF-TF treatment (P<0.05), and the tumor masses in 2 of 10 mice were almost disappeared on Day 14 after the first treatment. In addition, valid thrombogenesis and tumor necrosis were observed in the tumor tissues injected with rVEGF-TF. Our results demonstrate that occlusion of tumor vasculature with rVEGF-TF is potentially an effective approach for cancer therapy.

3D biofabrication of vascular networks for tissue regeneration:A report on recent advances

Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue engineered constructs largely depends on the incorporation of a stable vascular network that eventually anastomoses with the host vasculature to support the various biological functions of embedded cells. In recent years, significant progress has been achieved with respect to extrusion, laser, micro-molding, and electrospinning-based techniques that allow the fabrication of any geometry in a layer-by-layer fashion. Moreover, decellularized matrix, self-assembled structures, and cell sheets have been explored to replace the biopolymers needed for scaffold fabrication. While the techniques have evolved to create specific tissues or organs with outstanding geometric precision, formation of interconnected, functional, and perfused vascular networks remains a challenge. This article briefly reviews recent progress in 3D fabrication approaches used to fabricate vascular networks with incorporated cells, angiogenic factors, proteins, and/or peptides. The influence of the fabricated network on blood vessel formation, and the various features, merits, and shortcomings of the various fabrication techniques are discussed and summarized.

Leading Approaches to Vascularize Kidney Constructs in Tissue Engineering

There is an unprecedented need for new treatments for renal failure,as the incidence of this disease is increasing disproportionately to advancements in therapies.Current treatments are limited by the availability of viable organs,for which there is a worldwide lack.These treatment modalities also require a substantial amount of infrastructure,significantly limiting the access to care in most countries.Kidney tissue engineering approaches promise to develop alternative solutions that address many of the inadequacies in current care.Although many advancements have been made—primarily in the past decade—in biofabrication and whole-organ tissue engineering,many challenges remain.One major hindrance to the progress of current tissue engineering approaches is establishing successful vascularization of developed engineered tissue constructs.This review focuses on the recent advancements that address the vascular challenge,including the biofabrication of vasculature,whole-organ engineering through decellularization and recellularization approaches,microscale organogenesis,and vascularization using organoids in the context of kidney tissue engineering.We also highlight the specific challenges that remain in developing successful strategies capable of clinical translation.