Artifical Blood Vessels Made From Thermoplastic Polyurethane Polymers

Wherever we find some of the worse medical events – heart attacks, strokes, pulmonary embolisms, we find blocked blood vessels. Obstructed blood vessels are a lurking time bomb in our bodies and they usually have to be replaced. Blood vessel replacement requires cutting another blood vessel from another part of the body or the implantation of artificial vascular prostheses.

A new option might emerge in the future, however. Vienna University of Technology, in collaboration with the Vienna Medical University developed artificial blood vessels that were fabricated from specialized elastomer material that have excellent mechanical properties. After implantation, these artificial blood vessels are dissolved and replaced by the body’s own blood vessels. At the end of the healing process, natural, fully functional blood vessels are once again in place. The technique works quite well in tissue cultures systems, but now it has been shown to successfully regenerate blood vessels in laboratory animals, specifically rats.

Atherosclerotic vascular disorders, in which blood vessels are obstructed by cholesterol-filled plaques, are one of the most common causes of death in industrialized countries. Typically, patients are treated with a bypass operation, and for such procedures, blood vessels are extirpated from another part of the patient’s body and used to replace the damaged vessel. This creates a new wound and a new area of the body with less than optimal blood supply that must heal. Also, the transplanted vessel rarely has the properties necessary to thrive in its new location.

This new strategy to replace diseased blood vessels is the result of a fruitful collaboration between Vienna University of Technology (or TU Wien, which is short for Technische Universität Wien) and the Medical University of Vienna. Hopefully the success of this research will cause artificially manufactured vessels to be used more frequently in future.

To make an artificial blood vessel, the most important thing is to start with the right material. The material must be compatible with body tissue, and pliable enough to be formed into a small diameter tube that is not easily blocked by blood clots.

Extensive work at TU Wien has resulted in the development of new polymers. “These are so-called thermoplastic polyurethanes,” explains Robert Liska from the Institute of Applied Synthetic Chemistry of TU Wien.  “By selecting very specific molecular building blocks we have succeeded in synthesizing a polymer with the desired properties.”

In order to generate artificial blood vessels from their thermoplastic polyurethanes, TU Wien materials scientists spun polymer solutions in an electrical field. This allowed them to form very fine threads and that could be wound into a spool. “The wall of these artificial blood vessels is very similar to that of natural ones,” says Heinz Schima of the Medical University of Vienna. The thermoplastic polyurethanes form a polymer fabric that is slightly porous and allows a small amount of blood to leak through it. This also enriches the blood vessel wall with growth factors, which encourages the migration of endothelial progenitor cells. Martina Marchetti-Deschmann at TU Wien studied the interaction between the thermoplastic polyurethane material and blood by using spatially resolved mass spectrometry.

This new technology has already proven to successfully form functional blood vessels in rats. “The rats’ blood vessels were examined six months after insertion of the vascular prostheses,” says Helga Bergmeister of MedUni Vienna. “We did not find any aneurysms, thromboses or inflammation. Endogenous cells had colonized the vascular prostheses and turned the artificial constructs into natural body tissue.” In fact, the body’s own blood vessel-forming tissues re-grew significantly faster than expected, which shortened the degradation period of the plastic tubes and their replacement with the body’s own endothelial cells. TU Wein and the Medical University of Vienna are making further adaptations to the material.

A few more preclinical trials are necessary before the artificial blood vessels can be used in human clinical trials. However, based on the results so far, the research team is very confident that the new method will prove itself for use in humans in a few years’ time.

This project was recently awarded PRIZE prototype funding from Austria Wirtschaftsservice (AWS).

Stem Cell Treatments for Stroke: A Tale of Two Trials

Two different clinical trials that examined the efficacy of stem cell treatments after a stroke have yielded very different results.

“Stroke” refers to a serious medical condition that occurs when the blood supply to the brain is disrupted by blockage of or injury to blood vessels that supply the brain with blood. Strokes cause a loss of, or reduction in, brain function. There are two main types of strokes. Ischemic stroke accounts for about 80% of strokes. Ischemic strokes result from the cessation of blood flow to an area of the brain because of a blood clot. Hemorrhagic stroke occurs if there is a leakage of blood into the brain because a blood vessel has burst. The bleed into the brain increases the pressure on the brain and leads to brain damage.

In the two clinical trials discussed in this post, both treatments were designed to address ischemic strokes, which disrupt the blood supply to the brain and starve brain cells of oxygen, causing them to die. Brain scans of patients who have suffered from an ischemic stroke may reveal large areas of damaged brain tissue. People who have had a stroke may experience difficulties with speech and language, orientation and movement, or memory. Such problems can be permanent or temporary.

Any advances in the treatment of stroke are particularly Currently, the only available treatment is to administer anti-clotting agents to dissolve the clot that has blocked the blood flow to the brain. Unfortunately, this treatment must be provided early and only a small proportion of patients get to hospital in time to be treated in this way.

There are no existing treatments for an ischemic stroke beyond the initial acute phase. However, rehabilitation can alleviate the disabilities caused by a stroke.

The European Stroke Organization released the results of large clinical trials on the treatment of strokes with CTX0E03 human neural stem cells. The PISCES trial, as it is known, is a phase I trial, and such trials usually involve giving a small number of people a new treatment to see if it is safe. Phase I trials are not designed to test if the treatment is effective, so any positive results from a Phase I trial should be treated with some caution.

This study examined the safety and tolerability of a stem cell therapy called ReN001 in the treatment of ischemic stroke.

11 males with long-term disability between 6 and 60 months after a stroke. None of the patients showed any cell-related or immunological adverse events. Patients did show sustained reductions in neurological impairment and spasticity compared to their stable pre-treatment baseline performance.

This clinical trial is a win for ReNeuron, the company that developed, makes and markets, ReN001. A Phase II is being planned.

A second clinical trial examined the efficacy of Athersys, Inc. MultiStem treatment for ischemic stroke. This phase II trial was designed to evaluate the efficacy of the product in stroke patients. 65 patients were treated with MultiStem and 61 were given the placebo. Unfortunately, even though the MultiStem treatment was safe as well tolerated, the cell therapy did not produce any statistically significant differences at 90 days in patients compared with a placebo.

Even though the data was disappointing, a second look at the data showed something interesting. When the 27 stroke patients who had received the MultiStem treatment 24-26 hours after the stroke were compared with all the other patients, it became clear that these patients did the best. Therefore, this trial seems to indicate that the window of treatment for MultiStem after a stroke is 24-36 hours and after 36 hours it works no better than placebo.

“Unfortunately, we just didn’t have the window right for this study,” Athersys Chief Operating Officer William Lehmann Reuters News Service. “We believe investors should see this as a sign that MultiStem works.”

The MultiStem treatment was also associated with lower rates of mortality and life threatening adverse effects, infections and lung-related events. Nine patients who had received the placebo died during the 90 day period (14.8%) while only four who received the MultiStem treatment died (6.2%).

The CEO of Athersys, Gil Van Bokkelen, said: “While the trial did not achieve the primary or component secondary endpoints, we believe the evidence indicating that patients who received MultiStem treatment early appeared to exhibit meaningfully better recovery is important and promising.”

This randomized, double-blind, placebo-controlled Phase 2 study is being conducted at sites in the United States and the United Kingdom.

Fat-Based Stem Cells Speed the Healing of Bed Sores in Animals

Pressure ulcers, which are also knows as bedsores (or decubitus ulcers) are localized injuries to the skin that can also include the underlying tissue that usually occur as a result of pressure, or pressure in combination with rubbing or friction. They tend to occur some sort of bony prominence such as elbows, hips, shoulders, ankles, back of the head, and other such places. More than 2.5 million patients each year in the U.S. require treatment for pressure ulcers, and the elderly are at particularly high risk for these lesions. Currently, therapies for pressure ulcers consist of conservative medical management for shallow lesions and aggressive debridement and surgery for deeper lesions.

Jeffery Gimble and his colleagues from the Tulane University School of Medicine in New Orleans, Louisiana, used a mouse model for pressure ulcers to test the ability of fat-derived stromal/stem cell treatment to accelerate and enhance the healing of pressure ulcers.  The dorsal skin of both young (2 months old) and old (20 months old) C57BL/6J female mice was pinched between external magnets for 12 hours over 2 consecutive days. This treatment initiated a pressure ulcer, and one day after induction of the pressure ulcers, some of these mice were injected with fat-derived stromal stem cells that had been isolated from healthy mice that were of the same genetic lineage as the injured mice. However, the donor mice were genetically engineered to express a green fluorescent protein in all their tissues. Other mice were treated with injections of saline-treated controls.

The mice that were injected with fat-derived stromal/stem cells displayed a cell-concentration-dependent acceleration of wound closure. The cell-injected mice also showed improved epidermal/dermal architecture, increased fat deposition, and reduced inflammation at the sites of injury. Interestingly, these fat-derived stem cell-induced improvements occurred in both young and elderly mice. However, the gene expression profile of genes involved in the making of blood vessels, regulating the immune system, and tissue repair differed according to the age of the mice, with younger mice making more of these genes that their older counterparts. These results are consistent with clinical reports of the improved skin architecture after fat grafting in patients with thermal injuries.

This current proof-of-principle study sets the stage for clinical translation of the transplantation of fat-based stem cells as a treatment of pressure ulcers.

MS Patients in Phase 1 Stem Cell Trial Show Improvement

Phase 1 clinical studies are designed to determine the proper dosage of an agent and to assess the safety of a drug. Phase 1 studies are not designed to determine if the patients who take the drug or agent benefit from it. Therefore, it is highly gratifying to see a medical agent produce distinct improvements in a phase 1 study.

The Tisch MS Research Center of New York (Tisch MSRCNY) has announced in an April 23rd press release that patients enrolled in their FDA-approved Phase I trial using autologous neural stem cells in the treatment of multiple sclerosis (MS) show significant improvements. These results were presented during the Multiple Sclerosis Highlights in the Field session at the 67th American Academy of Neurology (AAN) Annual Meeting in Washington, D.C.

MS is a chronic autoimmune disease of the central nervous system caused by attacks against the myelin sheath by the patient’s own immune system. The destruction of the myelin sheath causes systemic neurodegeneration. MS affects more than 2.3 million people worldwide.

In its interim analysis of their data, Tisch MSRCNY researchers reported that six of the nine patients treated with stem cells show increased motor strength, improved bladder function and an enhanced quality of life. Significantly, these treatments are well tolerated and, to date, no serious adverse events were reported.

“This preliminary data is encouraging because in addition to helping establish safety and tolerability, the trial is yielding some positive therapeutic results even at this early stage,” said Dr. Saud A. Sadiq, Chief Research Scientist at Tisch MSRCNY and the study’s principal investigator. Sadiq cautioned that these results result from an interim analysis and definitive conclusions will only be made upon completion of the trial.

The Tisch MSRCNY study investigates a pioneering regenerative strategy that utilizes stem cells harvested from the patient’s own bone marrow.  Specifically, a special stem cell population called “MSC-NPs” or mesenchymal stem cell-derived neural progenitors are isolated from bone marrow and used in this clinical trial.  MSC-NPs represent a neural subpopulation of bone marrow-derived MSCs with reduced mesodermal pluripotency and minimized risk of ectopic differentiation.  In preclinical studies in laboratory mice afflicted with “experimental autoimmune encephalomyelitis” (an excellent model system for MS), Tisch MSRCNY scientists established that three doses of MSC-NPs delivered intrathecally (IT) resulted in improved neurological function associated with suppression of local inflammatory response and trophic support for damaged cells at lesion sites.

Once the MSC-NPs were isolated from the patient’s bone marrow stem cell, they were injected intrathecally, that is, into the cerebrospinal fluid surrounding the spinal cord, in 20 participants who meet the inclusion criteria for the trial. This is an open label safety and tolerability study, which means that both the physicians and patients know what treatments that are giving and receiving in contrast to blinded studies. All clinical activities in this study will be are conducted at Tisch MS Research Center of New York or at affiliated International Multiple Sclerosis Management Practiced. The interim analysis reports on the first nine patients who received at least one treatment of stem cells.

Study patient Vicky Gill, a married mother of two whose husband, Michael, also has MS, has already experienced the positive benefits of the therapy. “For the past six years, I would fall frequently, had very limited movement in my legs and always walked with my cane. After just two stem cell treatments, I am now gaining sensation and function I thought was totally lost, have not had any recent falls and at times don’t need a cane at all.”

The patients in this trial will receive three rounds of injections at three-month intervals. Safety and efficacy parameters will be evaluated in all patients through regular follow-up visits. Dr. Sadiq plans to continue and complete the Phase I study and if these positive trends continue, move on to a multi-center Phase II efficacy trial.

Cardio3 BioSciences Announces First Patient Enrollment in New CART Therapy Trial

The European cell therapy company Cardio3 BioSciences (C3BS) announced the enrollment of the first patient in its Phase I clinical trial to evaluate the Company’s lead CAR T-Cell therapy. This CART cell therapy is called “NKG2D CAR T-Cell” and will be tested in blood cancer patients with acute myeloid leukemia (AML) or multiple myeloma (MM). In the coming days T lymphocytes will be isolated from patients’ peripheral blood, cultured and genetically engineered to express the chimeric antigen receptor. Then these NKG2D CAR T-Cells will be infused into the patients.

NKG2D CAR T-Cells express a chimeric antigen receptor that was constructed by using the native sequence of non-engineered natural killer cell (NK cell) receptors. This receptor has the ability to target a broad range of solid tumors and blood cancers by targeting specific molecules present on cell surfaces of numerous types cancers. NKG2D CAR T-Cell is a potential new treatment option for patients with solid tumors such as breast, colorectal, lung, liver, ovarian and bladder cancer, in addition to the blood cancers targeted in this trial. The concepts that undergird this clinical trial were discovered at Dartmouth College by Professor Charles Sentman, and has been published in numerous peer-reviewed publications such as Journal of Immunology, Cancer Research and Blood.

NKG2D CAR T-Cell received an Investigational New Drug (IND) clearance, under the name CM-CS1, from the U.S. Food and Drug Administration (FDA) in July 2014 for the Phase I clinical trial in blood-borne cancers.

Dr. Christian Homsy, CEO of Cardio3 BioSciences, said: “We are extremely pleased to initiate enrollment of the first Phase I trial of our CAR T-Cell therapy program with lead product candidate NKG2D CAR T-Cell, in-line with our previously disclosed clinical development plan. As AML and MM are two underserved blood cancer subtypes, there is a clear need for new, viable treatment options. To date, NKG2D CAR T-Cell therapies have demonstrated the prevention of tumor development and increased survival in preclinical animal models, suggesting that NKG2D CAR T-Cell has the potential to be one such therapy.”

Cardio3 BioSciences expects to complete the study in mid-2016 and will provide updates as the trial advances. Because it is a Phase I trial, it will assess the safety and feasibility of NKG2D CAR T-Cell as primary endpoints, with secondary endpoints including clinical effectiveness. If the trial is successful, however, it might provide alternative therapies for patients with a variety of cancers.

Making Purkinje Cells in a Culture Dish

The beating heart is functionally divided into two levels; an upper set of chamber and a lower set of chambers.  The heart beat originates in upper chambers, but that signal to beat must be relayed to the lower chambers of the heart.  However does this signal get to the bottom of the heart?  The answer is that there is an extension cord that relays the signal to beat from the top of the heart to the lower chambers of the heart.  This extension cord comes in the form of a conduction system that consists of modified cells that do not contract, but conduct electrochemical signals from the upper chambers of the heart to the lower chambers.


The beat originates in the upper part of the left atrium (upper chamber) in the so-called pacemaker or sinoatrial node.  The signal to beat spreads rapidly across the atrial tissue and the a transmission node called the atrioventricular node at the bottom of the heart.  Once the signal to beat gets to the atrioventricular node, that signal goes to the conductive tissues in the septum of the heart called the “bundle of His” or atrioventricular bundle.  From there, the signal splits into the left and right bundle branches that swing around bottom of the heart into the ventricle walls.  Tiny extensions of the conduction system called “purkinje fibers” move into the walls of the ventricles.  These purkinje fibers function to control cardiac action potentials essential for a consistent heartbeat.

Several studies suggest that dysfunctional purkinje fibers are a potential source of arrhythmias in several heart syndromes.  However, how purkinje fiber dysfunction is responsible for causing arrhythmias has not been fully studied.  In order to begin this studying the role of purkinje fibers in arrhythmias, the laboratory of Glenn I. Fishman (New York University School of Medicine, USA) has generated an engineered mouse embryonic stem cell (ESC) line which can generate huge numbers of purkinje fiber cells.  Normally, when embryonic stem cells are differentiated into heart muscle cells (cardiomyocytes), purkinje cells constitute a very minor, even rare cell sub‐population (see Maass K, Shekhar A, Lu J, et al. Isolation and characterization of embryonic stem cell-derived cardiac purkinje cells. Stem Cells 2015;33:1102-1112).

According to previous expression studies, Fishman and others utilized ESCs that expressed Green Fluorescent Protein (GFP) under the control of the Cntn2 promoter.  The Cntn2 gene encodes the Contacting-2 protein, which marks those cells that will differentiate into Purkinje fiber conduction network cells (Pallante BA, et al. Circ Arrhythm Electrophysiol 2010;3:186-194;Kim EE, et al. The Journal of clinical investigation 2014;124:5027-5036).  Cntn2, however is not a perfect marker because it is also expressed in certain neuronal cells.  Therefore an additional marker was used; “MHCα‐mCherry.”  MHCα‐mCherry expressed a very brightly colored protein under the control of the myosin heavy chain gene promoter.  Because the alpha-myosin heavy chain is a heart muscle-specific protein, this brightly-colored protein is only expressed in heart-specific cells. Any cells that express both the Cntn2-GFP and the MHCα‐mCherry are almost certainly purkinje fiber cells.

Fishman and his team differentiated mouse ESCs into purkinje fiber cells and characterized the parallel activation of αMHC and Cntn2 in the developing murine heart.  ESC-derived purkinje fibers made up around 2% of the cell population at 4 weeks, and appeared long and pointy.  They also expressed a range of proteins similar to that of endogenous purkinje fiber cells, such as Cntn2, Troponin T (in a sarcomeric pattern, no less), and the conduction‐system specific connexin40 gap junctional protein.  Further analysis demonstrated the heightened expression of many genes associated with the cardiac conduction system, such as Nkx2‐5, Connexin40, HCN4, CACNA1G, Scn5a, and SCN10A.  The use of patch-clamping showed that these cultured cells  had similar electrophysiological properties to that of endogenous PCs; a highly important characteristic.

In combination with ESC-derived sinoatrial cells (see Scavone A, et al. Circulation research 2013;113:389-398), pacemaker cells (see Morikawa K, et al. Pacing Clin Electrophysiol 2010;33:290-303), and atrial‐like cardiomyocytes (Josowitz R, et al. PLoS One 2014;9:e101316), the creation of PC cells in this study may represent an extremely exciting step towards cell therapy for the failing heart. These data represent a useful strategy for the production of a large amount of a useful cell type from a heterogeneous cardiac cell population, which may be used to inform on diverse study areas including developmental biology, disease pathogenesis and anti‐arrhythmic drug screening. The authors themselves hope that using patient-specific fibroblasts and a direct reprogramming process, PCs may be used to treat heritable, acquired and post‐surgical damage to the heart’s conduction system in a patient-tailored manner.

Using Cord Blood Stem Cells to “Re-educate” White Blood Cells and Treat Hair Loss

Alopecia areata (AA) is an autoimmune disease that targets the hair follicles. It affects the quality of life and self-esteem of patients because they lose their hair. Is there a way to treat this disease without suppressing the immune system?

Yong Zhao and from Tianhe Stem Cell Biotechnologies in Shandong, China and his collaborators used a so-called “Stem Cell Educator therapy” in which they took the patient’s blood and circulated it through a closed-loop system that separated mononuclear cells from the whole blood, and then allowed those cells to briefly interact with adherent human cord blood-derived multipotent stem cells (CB-SC). After this interaction, the mononuclear cells were returned to the patient’s circulation. This procedure uses the cord blood cells to “educate” the white blood cells of the patient to not attack the patient’s hair follicles.

In an open-label, phase 1/phase 2 study, nine patients with severe AA received one treatment with the Stem Cell Educator therapy. These patients were about 20 years old and had lost their hair, on the average, about 5 years ago.

All these patients experienced improved hair regrowth and quality of life after receiving Stem Cell Educator therapy.  Furthermore, analyses of immune cells from the blood of treated patients showed that the types of immune cells that attack tissues decreased and the number of cells that regulate the immune response increased. Also, investigations of hair follicles in the treated patients revealed that the restored hair follicles expressed a ring of transforming growth factor beta 1 (TGF-β1) around the hair follicles. TGF-β1 is a secreted molecule that down-regulates the immune response and prevents immune cells from attacking your own tissue. The fact that the hair follicles secreted all this TGF-β1 shows that the restored hair follicles had steeled them against the immune system.

How did the cord blood cells do this? By culturing white blood cells with cord blood cells in cell culture, Zhao and others showed that the human cord blood-derived multipotent stem cells induced white blood cells to increase their expression of molecules that are known to tame self-destructive white blood cells. Thus the cord blood stem cells secrete regulatory molecules that change the character of the immune cells so that they no longer attack the hair follicles.

These clinical data demonstrate the safety and efficacy of the Stem Cell Educator therapy for the treatment of AA. This is a very innovative approach that can produce lasting improvement in hair regrowth in subjects with moderate or severe AA.