Integration of Vasculature Network in Organoids.

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The prevalence of diabetes mellitus and obesity continues to increase globally. Diabetic vascular complications are the main chronic diabetic complications and associated with mortality and disability. Angiogenesis is a key pathological characteristic of diabetic microvascular complications. However, there are two tissue-specific paradoxical changes in the angiogenesis in diabetic microvascular complications: an excessive uncontrolled formation of premature blood vessels in some tissues, such as the retina, and a deficiency in the formation of small blood vessels in peripheral tissues, such as the skin. This review will discuss the paradoxical phenomena of angiogenesis and its underlying mechanism in obesity, diabetes and diabetic complications.

Researchers identify ovarian cancer biomarkers Finding could be first step toward new screening tool, treatment targetResearchers have identified markers unique to the cells of blood vessels running through ovarian tumors. The finding, while preliminary, could one day improve screening, diagnosis and treatment for this disease.The team of researchers from the University of Michigan, University of Pennsylvania, and universities in Greece and Italy used a laser technique to isolate blood vessel cells from 21 ovarian tumors and four normal ovarian tissue samples. From there, they were able to determine which genes the vascular cells expressed.The results identified more than 70 markers that were present in large amounts in the blood vessels of cancer tissue but not in the vessels of normal tissues. The researchers went on to study in detail 12 markers that had not previously been linked to tumor blood vessels. The study appears in the March 1, 2007 issue of the Journal of Clinical Oncology."Some of these genes, depending on how highly expressed they were in the tumor vasculature, were also prognostic of a patient's survival. We suspect when these genes are highly expressed it may be a sign of a tumor that's able to grow blood vessels more efficiently, and therefore is more aggressive. This may help us down the road in treatment decisions," says lead study author Ronald Buckanovich, M.D., Ph.D., assistant professor of internal medicine and obstetrics and gynecology at the University of Michigan Medical School. Buckanovich was at the University of Pennsylvania when he conducted this research.The study analyzed the largest number of samples to date in tumor vasculature, or blood vessel, profiling. While many of the genes identified in this analysis have been shown previously to be involved in tumor vasculatures for other cancer types, several of the markers appear to be new. In addition, the researchers were able to determine that some of the markers present in large amounts in ovarian tumors were not expressed by normal ovaries or other healthy organs. The researchers also found these markers were not present in normal reproductive tissues that experience blood vessel growth, such as the placenta or endometrium. This suggests that the markers are specific to tumors and would not be mistaken for normal blood vessel growth in women of reproductive age.If the markers do prove to be specific to ovarian tumors, researchers believe that could be a new avenue to develop drugs that would target the blood vessels and strangle the tumor.Biomarkers are also seen in other cancer types as a potential screening tool. A new way of detecting ovarian cancer could make a significant dent in this disease, where 70 percent of patients are diagnosed after the tumor has grown large or spread. There are few or no symptoms early in the disease and no effective screening tests. Early diagnosis is crucial, marking the difference between a 95 percent survival rate for cancers found at the earliest stage and 20 percent survival among patients diagnosed with advanced disease."All the things we could hope for are present with this approach: It has potential for diagnosis, imaging, treatment and prognosis. It needs more work and much more confirmation, but our early results are promising," Buckanovich says.Continued research will look at developing antibodies and methods to detect these novel proteins. "In some cases, these are genes that many people have never worked on before," Buckanovich says.The American Cancer Society estimates 22,430 women will be diagnosed with ovarian cancer this year and 15,280 women will die from it.The research is very preliminary at this point. Any potential screening or treatment benefit would be many years in the future. For information about currently available therapies, call the Cancer AnswerLine at 800-865-1125 or visit their web page.In addition to Buckanovich, study authors were Dimitra Sasaroli, Anne O'Brien-Jenkins, Jeffrey Botbyl, Rachel Hammond, Lance A. Liotta, Phyllis A. Gimotty and George Coukos, all from the University of Pennsylvania; Dionysios Katsaros of the University of Turin in Italy; and Raphael Sandaltzopoulos of the Democritus University of Thrace in Greece.Funding for the study was from the National Institutes of Health, a National Cancer Institute Specialized Program of Research Excellence (SPORE) grant, the U.S. Army Medical Research and Materiel Command Grant, the Marcia and Philip Rothblum Foundation and the Ovarian Cancer Research Fund. The laser-capture microdissection facility was supported by the Fannie Rippel Foundation.

Mesenchymal stem cells (MSCs)-populated small diameter (6 mm) vascular constructs were fabricated. The constructs mimicked the native vessels in multiple levels, i.e. having similar structure and morphology to that of the extracellular matrix in the native blood vessels; recapitulating mechanical properties such as compliance and burst pressure of the native blood vessels; simulating the highly cellularized nature of the native blood vessels; and having an antithrombogenic lumen. The constructs were fabricated by simultaneously assembling poly(ester carbonate urethane) urea nanofibers and MSCs in an electrical field. The nanofibers had a diameter similar to that of the collagen and elastin fibers in the native blood vessels. MSCs were distributed evenly in the constructs. The constructs were highly cellularized when the cell loading density was exceeded 6 million/ml. The vascular constructs were strong and flexible with breaking strains of 144–202%, tensile strengths of 0.80–1.29 MPa, compliances of 13.23–21.96 × 10−4 mmHg−1, stiffness indexes of 7.3–9.8, and burst pressures greater than 1700 mmHg. These mechanical properties were similar to those of the native blood vessels. In vitro platelet deposition experiments showed that platelet adhesion was remarkably decreased in the MSCs-populated constructs compared to that in the construct without MSCs. An increase in MSC density in the constructs further decreased platelet adhesion. When cultured in a spinner flask, MSCs maintained their mitochondria viability and cell number during a two-week culture period, as confirmed by MTT and dsDNA assays. These vascular constructs may hold the potential to regenerate functional small diameter vessels for cardiovascular tissue repair.

Bacterial cellulose/fibrin composites were treated with glutaraldehyde in order to crosslink the polymers and allow better match of the mechanical properties with those of native small-diameter blood vessels. Tensile and viscoelastic properties of the glutaraldehyde treated composites were determined from tensile static tests and cyclic creep tests, respectively. Glutaraldehyde-treated (bacterial cellulose) BC/fibrin composites exhibited tensile strength and modulus comparable to a reference small-diameter blood vessel; namely a bovine coronary artery. However, the breaking strain of the glutaraldehyde-treated composites was still well below that of the native blood vessel. Yet a long strain hardening plateau was induced by glutaraldehyde treatment which resembled the stress–strain response of the native blood vessel. Tensile cyclic creep test indicated that the time-dependent viscoelastic behavior of glutaraldehyde-treated BC/fibrin composites was comparable to that of the native blood vessel. Covalent bonding between BC and fibrin occurred via glutaraldehyde, affording mechanical properties comparable to that of the native small blood vessel.

Introduction: A vascular scaffold must not only support appropriate structural integrity until neotissue can form, but also closely mimic the strength and compliance of native blood vessels. Hemocompatibility is also clearly a crucial factor to raise success of the engineered construct since the vascular scaffold comes in contact with blood. The degradation profile of the scaffold is another important criterion to consider for successful applications in tissue engineering of load-bearing structures like blood vessel tissues. A tissue-engineered vascular graft requires complete scaffold degradation with well-defined cellular organization and tissue remodeling. Results: To cover all these required features, we carried out the blend electrospinning to fabricate nanofibers of poly(L-lactide acid-co-poly e-caprolactone) (PLCL), a biodegradable and compliant polymer, gelatin (Gel), a biodegradable and commercially available natural biopolymer possessing many integrin binding sites (such as RGD) for cell adhesion, and Tecophilic (TP), a hydrophilic, elastic and hemocompatible polyether-based thermoplastic aliphatic polyurethane, with a weight ratio of 60:20:20 (PGT;60/20/20) resulted in creation of a compliant, hemocompatible and biodegradable scaffold. The nanofibrous structure of the scaffold was visualized using a scanning electron microscope (SEM). The surface characterization of scaffold was carried out using ATR-FTIR spectroscopic analysis. For evaluating the potential of electrospun PGT;60/20/20 scaffold as a substrate for vascular regeneration, we cultured human aortic smooth muscle cells (SMCs) on the scaffold and studied the biocompatibility of the structure by performing the proliferation assay and cell morphology assessment. Conclusion: SEM images demonstrated that electrospun PGT;60/20/20 nanofibers were successfully produced with a fiber diameter of 459±198 nm which revealed a significant reduction compared to fiber diameter of electrospun pure PLCL and pure TP. ATR-FTIR analysis confirms the presence of all components within the fibers. Comparing the behavior of SMCs on PGT;60/20/20 scaffolds with that on electrospun PLCL and TP scaffolds confirmed the potential use of PGT;60/20/20 nanofibers in blood vessel tissue engineering.

We have developed a tissue-engineering approach for the production of a completely biological blood vessel from cultured human cells. In the present study, we took advantage of this tissue-engineering method to demonstrate that it can be used to reproduce the subtle differences in the expression of receptors present on the media of native human blood vessels. Indeed, a small percentage (3 of 18) of native human umbilical cord veins (HUCVs) responded to endothelin, the most powerful vasopressor agent known to date, via both endothelin A (ET(A)) and endothelin B (ET(B)) receptor activation. In contrast, most HUCVs tested responded to ET via ET(A) receptor activation only. Tissue-engineered vascular media (TEVM) were next reconstructed by using vascular smooth muscle cells (VSMCs) isolated and cultured from HUCVs expressing both ET(A) and ET(B) receptors to determine the functional integrity of our TEVM model. The reconstructed TEVM presents an endothelin response similar to that of respective HUCVs from which VSMCs were isolated. Reverse transcriptase polymerase chain reaction on TEVM reconstructed in vitro correlated these vasocontractile profiles by showing the presence of messenger RNA for both ET(A) and ET(B) receptors. Taken together with recently published results on TEVM expressing only ET(A) receptor, these results show that our reconstructed TEVM present a similar ET response profile as the blood vessel from which the VSMCs were isolated and cultured. These findings indicate that subtle differences, such as receptor expression, are preserved in the reconstructed tissue. Therefore, our TEVM offers a valuable human in vitro model with which to study the functionality of human blood vessels, such as their vasoactive response, or to perform pharmacologic studies.

Initial clinical feasibility with the small-diameter chitosan artificial vascular prosthesis has been reported previously. Here, we present the results of mechanical properties of artificial vascular prosthesis with 2, 3, and 4 mm inner diameter (ID) and compare some of the properties with the native blood vessel of dog femoral artery. Thickness wall measurement demonstrated the average wall thickness of the artificial vascular prosthesis with 2, 3, and 4 mm ID and the native blood vessel of the dog femoral artery with 3 mm ID were 0.54 ± 0.022 mm, 0.71 ± 0.032 mm, 0.79 ± 0.026 mm, and 0.67 ± 0.22 mm (n = 20). Water absorption rate of 226.02% ± 8.17%, 216.13% ± 4.86%, and 205.69% ± 4.34% were obtained from 2-, 3-, and 4-mm-diameter artificial vascular prosthesis (n = 12), respectively. Water osmotic pressure of the 2-, 3-, and 4-mm-diameter artificial vascular prosthesis was 39.25 ± 3.35 mmHg, 34.2 ± 4.54 mmHg, and 28.00 ± 2.72 mmHg (n = 20), respectively. Water osmotic amount of the 2-, 3-, and 4-cm-diameter artificial vascular prosthesis (n = 20) was 4.90 ± 0.47 mL/(min cm(2) ), 5.51 ± 0.21 mL/(min cm(2) ), and 6.24 ± 0.71 mL/(min cm(2) ), respectively. The ruptured stretching rate of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 1.59% ± 0.14%, 1.99% ± 0.24%, 2.52% ± 0.21%, and 32.16% ± 2.15%, respectively. The longitudinal tensile strength of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel was 8.58 ± 1.98 N, 19.75 ± 4.07 N, 22.92 ± 3.85 N, and 18.76 ± 2.05 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID and the native blood vessel in dry condition is 5.80 ± 0.51 N, 7.01 ± 0.32 N, 8.49 ± 0.56 N, and 7.92 ± 0.39 N, respectively. The suture retention of the artificial vascular prosthesis (n = 20) with 2, 3, and 4 mm ID in wet condition is 3.87 ± 0.43 N, 4.73 ± 0.37 N, 5.63 ± 0.36 N, and 7.92 ± 0.39 N, respectively. The compliance of the artificial vascular prosthesis with 2, 3, and 4 mm ID and the native blood vessel was 6.5% ± 2.6%/100 mmHg, 5.2% ± 1.5%/100 mmHg, 4.7% ± 1.3%/100 mmHg, and 10.3% ± 2.3%/100 mmHg, respectively. The data reported here fulfill the quality requirement of clinical use of this kind of biodegradable small diameter artificial vascular prosthesis.

Hydrostatic pressure stimulates the osteogenesis and angiogenesis of MSCs/HUVECs co-culture on porous PLGA scaffolds

The ability to regenerate tissue is different for each organism. Mice (Mus musculus) able to regenerate the 3rd phalange of a digit. The tissue regeneration process has four phases are the wound-healing phase, the blastema phase, the regeneration phase, and the maturation phase. Each phase has a different process and different activity of cells. Histological analysis is very important to see the activity of each cell in each phase of tissue regeneration. Through histological analysis we can find out the role of each cell in the tissue regeneration process as well as the processes that occur in tissue regeneration. In this study, we analyzed tissue histology in the digit tip mice at each regeneration phase post amputated. The phalanges were amputated on the 3rd phalanges of digit tip of 24 male mice which had been previously sedated using ketamine / xylazine. Digit tip were allowed to grow and regenerate, and samples were taken on days 0, 1, 3, 5, 10, 15, 25 after amputation. Histological analysis was performed using Hematoxylin-eosin staining on a sample preparation that had been made into paraffin blocks first. The histological showed that at the beginning of the wound, the tissue rapidly forms a thin epidermal layer to cover the wound. In the wound healing phase, some of embryonal cells proliferated and migrated actively. In the blastema phase, granule cells cluster to form various new tissues. In the regeneration phase, new tissue begins to form, such as blood vessel, muscle, bone, and epidermal tissue. In the regeneration phase on day 15, several new tissues have begun to form, such as blood vessel tissue, muscle, hemorrhoid, bone and epidermis. Finally, in the maturation phase on day 25, the tissue morphology process occurs and perfecting the digit tip mice tissue.

All human tissues present with unique mechanical properties critical to their function. This is achieved in part through the specific architecture of the extracellular matrix (ECM) fibres within each tissue. An example of this is seen in the walls of the vasculature where each layer presents with a unique ECM orientation critical to its functions. Current adopted vascular grafts to bypass a stenosed/damaged vessel fail to recapitulate this unique mechanical behaviour, particularly in the case of small diameter vessels (<6 mm), leading to failure. Therefore, in this study, melt-electrowriting (MEW) was adopted to produce a range of fibrous scaffolds to mimic the extracellular matrix (ECM) architecture of the tunica media of the vasculature, in an attempt to match the mechanical and biological behaviour of the native porcine tissue. Initially, the range of collagen architectures within the native vessel was determined, and subsequently replicated using MEW (winding angles (WA) 45°, 26.5°, 18.4°, 11.3°). These scaffolds recapitulated the anisotropic, non-linear mechanical behaviour of native carotid blood vessels. Moreover, these grafts facilitated human mesenchymal stem cell (hMSC) infiltration, differentiation, and ECM deposition that was independent of WA. The bioinspired MEW fibre architecture promoted cell alignment and preferential neo-tissue orientation in a manner similar to that seen in native tissue, particularly for WA 18.4° and 11.3°, which is a mandatory requirement for long-term survival of the regenerated tissue post-scaffold degradation. Lastly, the WA 18.4° was translated to a tubular graft and was shown to mirror the mechanical behaviour of small diameter vessels within physiological strain. Taken together, this study demonstrates the capacity to use MEW to fabricate bioinspired scaffolds to mimic the tunica media of vessels and recapitulate vascular mechanics which could act as a framework for small diameter graft development to guide tissue regeneration and orientation.

JMD Editorial Board

Vasculopathy is a pathological process occurring in the blood vessel wall, which could affect the haemostasis and physiological functions of all the vital tissues/organs and is one of the main underlying causes for a variety of human diseases including cardiovascular diseases. Current pharmacological interventions aiming to either delay or stop progression of vasculopathies are suboptimal, thus searching novel, targeted, risk-reducing therapeutic agents, or vascular grafts with full regenerative potential for patients with vascular abnormalities are urgently needed. Since first reported, pluripotent stem cells (PSCs), particularly human-induced PSCs, have open new avenue in all research disciplines including cardiovascular regenerative medicine and disease remodelling. Assisting with recent technological breakthroughs in tissue engineering, in vitro construction of tissue organoid made a tremendous stride in the past decade. In this review, we provide an update of the main signal pathways involved in vascular cell differentiation from human PSCs and an extensive overview of PSC-derived tissue organoids, highlighting the most recent discoveries in the field of blood vessel organoids as well as vascularization of other complex tissue organoids, with the aim of discussing the key cellular and molecular players in generating vascular organoids.

Aggressive Phenotype of Intravascular Lymphoma Relative to Other Malignant Intraabdominal Tumors Requiring Vascular Reconstruction