Achilles tendon injuries are somewhat common for professional, collegiate, and recreational athletes, and they are usually treated surgically. Torn tendons are reattached or patched with sutures.
A research group from Union Memorial Hospital, in Baltimore, Maryland has discovered that depositing stem cells onto sutures can lead to faster healing after surgery that also leads to stronger tendons.
Such a finding can lift the spirits of those who have had the misfortune of healing from an Achilles tendon repair procedure, Often, the patient has to keep their leg immobilized for days after surgery, and even after rehabilitation, tendon rupture remains a nagging risk.
This study showed, however, that when compared with traditional Achilles tendon repair surgery, laboratory animals that had mesenchymal stem cells from bone marrow embedded in their sutures healed faster and had tougher tendons that resisted post-surgical rupture.
Another bonus from this study was that the stem cells stayed in the tendon and promoted healing during the period when the patients are unable to their leg. Limb immobilization can cause muscle and tendon atrophy and may also cause adhesions. These can affect how strong and functional the muscle and tendon are after reattachment.
Not only did the stem cells encourage faster healing, by the tendon strength was great in the stem cell-treated group after four weeks. Hopefully these pre-clinical trials will give way to clinical trials with human patients.
A Duke University research team has combined synthetic scaffolding materials with gene delivery techniques to generate replacement cartilage precisely where it’s needed in the body.
The ingenious strategy utilized by this research project circumvents the need for large quantities of growth factors, which are expensive and difficult to apply after implantation. The Duke team led by Farshid Guilak, director of orthopedic research at Duke University Medical Center, used gene therapy to make stem cells that synthesize their own growth factors.
In brief, Guilak and his collaborators used genetically engineered viruses to transfer genes to stem cells embedded in a synthetic matrix. Upon infection, the stem cells grew and differentiated as needed, but the scaffolding provided the necessary structural cues for the stem cells to move to the proper configuration and form cartilage with the proper shape and biomechanical properties.
Guilak has devoted several years to developing biodegradable synthetic scaffolds that mimic the mechanical properties of cartilage. After testing many different scaffolds, he settled on a 3D woven poly(ε-caprolactone) scaffold, which is completely biodegradable and provides an excellent structural matrix for the synthesis of cartilage. However, an additional challenge for engineering good cartilage is to coax stem cells embed themselves in the scaffold while differentiating into cartilage-making cells, known as chondrocytes, after the scaffold has been implanted into a living organism.
One widely used strategy is to treat the stem cells with growth factors to induce chrondrocyte formation and cartilage production. Such cartilage can be implanted after it has been grown in the laboratory. However, this approach has some inherent limitations.
Guilak explained that “a major limitation in engineering tissue replacements has been the difficulty in delivering growth factors to the stem cells once they are implanted in the body.” Guilak continued: “There’s a limited amount of growth factor that you can put into the scaffolding, and once it’s released, it’s all gone. We need a method for long-term delivery of growth factors, and that’s where the gene therapy comes in.”
To tackle this perennial problem, Guilak tapped a talented colleague of his, Charles Gersbach, an assistant professor of biomedical engineering, who happens to also be a gene therapy expert.
Gersbach looked at the tissue engineering problem in an entirely new way and suggested that if the mountain will not come to Mohammed (that is to say if the growth factors cannot be given to stem cells after implantation), then Mohammed should grow his own mountain (the stem cells should be genetically engineered to make their own growth factors). Unfortunately, the conventional gene therapy methods are too complex to be commercially feasible. Typically, stem cells are collected, infected with genetically modified viruses that introduces new genes into them, grown to large numbers, and applied to synthetic cartilage scaffolds and implanted into the patient. Sounds like a headache? That’s because it is.
Fortunately, Gersbach had a slick gene therapy trick up his lab coat sleeve: “There are a few challenges with that process, one of them being that there are way too many extra steps,” said Gersbach. “So we turned to a technique I had previously developed that affixes the viruses that deliver the new genes onto a material’s surface.”
This new study combines Gersbach’s gene therapy technique—dubbed biomaterial-mediated gene delivery—to induce those human mesenchymal stem cells embedded in Guilak’s synthetic cartilage scaffolding to produce growth factor proteins (in particular a molecule called transforming growth factor β3 or TGF-β3). Based on the results of their experiments, the technique works and that the resulting synthetic, composite cartilage-like material is at least as good biochemically and biomechanically as if the growth factors were introduced in the laboratory.
“We want the new cartilage to form in and around the synthetic scaffold at a rate that can match or exceed the scaffold’s degradation,” said Jonathan Brunger, a graduate student who has spent time in both Guilak’s and Gersbach’s laboratories developing and testing the new technique. “So while the stem cells are making new tissue (in the body), the scaffold can withstand the load of the joint. In the ideal case, one would eventually end up with a viable cartilage tissue substitute replacing the synthetic material.”
This particular study examines cartilage regeneration, but Guilak and Gersbach hope that their technique could be applied to the regeneration of many different kinds of tissues, especially orthopaedic tissues such as tendons, ligaments and bones. Also, because the platform comes ready to use with any stem cell, it presents an important step toward commercialization.
“One of the advantages of our method is getting rid of the growth factor delivery, which is expensive and unstable, and replacing it with scaffolding functionalized with the viral gene carrier,” said Gersbach. “The virus-laden scaffolding could be mass-produced and just sitting in a clinic ready to go. We hope this gets us one step closer to a translatable product.”
Citation: “Scaffold-mediated lentiviral transduction for functional tissue engineering of cartilage.” Brunger, J.M., Huynh, N.P.T., Guenther, C.M., Perez-Pinera, P., Moutos, F.T., Sanchez-Adams, J., Gersbach C.A., and Guilak F. PNAS Plus, 2014. DOI: 10.1073/pnas.1321744111/-/DCSupplemental
Several preclinical trials in laboratory animals and clinical trials have definitively demonstrated the efficacy of stem cell treatments after a heart attack. However, these same studies have left several question largely unresolved. For example, when is the best time to treat acute heart attack patients? What is the appropriate stem cell dose? What is the best way to administer these stem cells? Is it better to use a patient’s own stem cells or stem cells from someone else?
A recent clinical trial from Soochow University in Suzhou, China has addressed the question of when to treat heart attack patients. Published in the Life Sciences section of the journal Science China, Yi Huan Chen and Xiao Mei Teng and their colleagues in the laboratory of Zen Ya Shen administered bone marrow-derived mesenchymal stromal cells at different times after a heart attack. Their study also examined the effects of mesenchymal stem cells transplants at different times after a heart attack in Taihu Meishan pigs. This combination of preclinical and clinical studies makes this paper a very powerful piece of research indeed.
The results of the clinical trial came from 42 heart attack patients who were treated 3 hours after suffering a heart attack, or 1 day, 3 days, 2 weeks or 4 weeks after a heart attack. The patients were evaluated with echocardiogram to ascertain heart function and magnetic resonance imaging of the heart to determine the size of the heart scar, the thickness of the heart wall, and the amount of blood pumped per heart beat (stroke volume).
When the data were complied and analyzed, patients who received their stem cell transplants 2-4 weeks after their heart attacks fared better than the other groups. The heart function improved substantially and the size of the infarct shrank the most. 4 weeks was better than 2 weeks,
The animal studies showed very similar results.
Eight patients were selected to receive additional stem cell transplants. These patients showed even greater improvements in heart function (ejection fraction improved to an average of 51.9% s opposed to 39.3% for the controls).
These results show that 2-4 weeks constitutes the optimal window for stem cell transplantation. If the transplant is given too early, then the environment of he heart is simply too hostile to support the survival of the stem cells. However, if the transplant is performed too late, the heart has already experiences a large amount of cell death, and a stem cell treatment might be superfluous. Instead 2-4 weeks appears to be the “sweet spot” when the heart is hospitable enough to support the survival of the transplanted stem cells and benefit from their healing properties. Also, this paper shows that multiple stem cell transplants a two different times to convey additional benefits, and should be considered under certain conditions.
Biomimetic matrices resemble living structures even though they are made from synthetic materials. Researchers in the laboratory of Shyni Varghese at the UC San Diego Jacobs School of Engineering have used calcium phosphate to direct mesenchymal stem cells to form bone. In doing so, Varghese and his colleagues have identified a surprising pathway from biomaterials to bone.
Varghese and his colleagues think that their work may point out new targets for treating bone defects, such as major fractures, and bone metabolic disorders such as osteoporosis.
The first goal of this research was to use materials to build something that looked like bone. This way, stem cells harvested from bone marrow (the squishy stuff inside our bones) could sense the presence of bone and differentiate into osteoblasts, the cells in our bodies that build bone.
“We knew for years that calcium phosphate-based materials promote osteogenic differentiation of stem cells, but none of use knew why.” said Varghese. “As engineers, we want to build something that is reproducible and consistent, so we need to know how building factors contribute to this end.”
Varghese and co-workers discovered that phosphate ions dissolved from calcium phosphate-based materials and these stray phosphate ions are taken up by the stem cells and used for the production of adenosine triphosphate or ATP. ATP is the energy currency of the cell, and it is the way cells store energy in a form that is readily usable for powering other reactions.
In stem cells, the generation of ATP eventually increases the intracellular concentration of the ATP breakdown product adenosine, and adenosine signals to stem cells to differentiate into osteoblasts and make bone.
Varghese said that she was surprised that “the biomaterials were connected to metabolic pathways. And we didn’t know how these metabolic pathways could influence stem cells,” and their commitment to bone formation.
These results also explain another clinical observation. Plastic surgeons have been using fat-based stem cells for eyelid lifts, breast augmentation, and other types of reconstructive surgeries. In once case, a plastic surgeon injected a dermal filler that contained calcium hydroxyapatite with the fat-based stem cells into a woman’s eyelid to provide an eye lift. However, the stem cells formed bone, and the poor lady’s lid painfully clicked every time she blinked and she had to have surgery to remove the ectopic bone. These results from Varghese’s laboratory explains why these fat-based stem cells formed bone in this case, and great care should be taken to never use such fillers in fat-based transplantation procedures.
According to a new study published in the January issue of the Journal of Bone and Joint Surgery(JBJS), a single stem cell injection after meniscus knee surgery can provide pain relief and aid in meniscus regrowth.
In the US alone, over one million knee arthroscopy procedures are performed each year. These surgeries are usually prescribed to treat tears to the wedge-shaped piece of cartilage on either side of the knee called the “meniscus.” The meniscus acts as an important shock absorber between the thighbone (femur) and the shinbone (tibia) at the knee-joint.
This novel study, “Adult Human Mesenchymal Stem Cells (MSC) Delivered via Intra-Articular Injection to the Knee, Following Partial Medial Meniscectomy,” examined 55 patients who had undergone a surgical removal or all or part of a torn meniscus (known as a partial medial meniscectomy). Each patient was randomly assigned to one of three treatment groups: Groups A, B and C. The 18 patients in group A received a “low-dose” injection of 50 million stem cells within seven to 10 days after their meniscus surgery. Another 18 patients in group B received a higher dose of 150 million stem cells seven to ten days after their knee surgery. The controls group consisted of 19 patients who received injections of sodium hyaluronate only (no stem cells). All patients were evaluated to determine the safety of the procedure, the degree of meniscus regeneration (i.e. with MRI and X-ray images), the overall condition of the knee-joint, and the clinical outcomes through two years. Most of the patients enrolled in this study had some arthritis, but patients with severe (level three or four) arthritis, were excluded from the study.
Most of the patients who had received stem cell treatments reported a significant reduction in pain. 24 percent of the patients in one MSC group and 6 percent of the other showed at least a 15 percent increase in meniscal volume at one year. Unfortunately, there was no additional increase in meniscal volume at year two.
“The results demonstrated that high doses of mesenchymal stem cells can be safely delivered in a concentrated manner to a knee-joint without abnormal tissue formation,” said lead study author C. Thomas Vangsness, Jr., MD. “No one has ever done that before.” In addition, “the patients with arthritis got strong improvement in pain” and some experienced meniscal regrowth.
The key findings of this study are that there no abnormal (ectopic) tissue formation or “clinically important” safety issues identified. Also, 24 percent of the patients in the low-dose injection group (A) and six percent of the high-dose injection group (B) at one year showed “significantly increased meniscal volume,” as determined by an MRI, and this increase did not continue into the second year, but remained stable (should future studies try a second injection of MSCs?). Third, none of the patients in the control group (non-MSC group) showed significant meniscus regrowth. Finally, patients with osteoarthritis experienced a reduction in pain in the stem cell treatment groups, but there was no reduction in pain in the control (non-MSC group).
“The results of this study suggest that mesenchymal stem cells have the potential to improve the overall condition of the knee joint,” said Dr. Vangsness. “I am very excited and encouraged” by the results. With the success of a single injection, “it begs the question: What if we give a series of injections?”
Researchers from the famed Mayo Clinic, in collaboration with scientists at a biopharmaceutical biotechnology company in Belgium have invented a specialized catheter for transplanting stem cells into a beating heart.
This new device contains a curved needle with graded openings along the shaft of the needle. The cells are released into the needle and out through the openings in the side of the needle shaft. This results in maximum retention of implanted stem cells to repair the heart.
“Although biotherapies are increasingly more sophisticated, the tools for delivering regenerative therapies demonstrate a limited capacity in achieving high cell retention in the heart,” said Atta Behfar, the lead author of this study and a cardiologist. “Retention of cells is, of course, crucial to an effective, practical therapy.”
Researchers from the Mayo Clinic Center for Regenerative Medicine in Rochester, MN and Cardio3 Biosciences in Mont-Saint-Guibert, Belgium, collaborated to develop the device. Development of this technology began by modeling the dynamic motions of the heart in a computer model. Once the Belgium group had refined this computer model, the model was tested in North America for safety and retention efficiency.
These experiments showed that the new, curved design of the catheter eliminates backflow and minimizes cell loss. The graded holes that go from small to large diameters decrease the pressures in the heart and this helps properly target the cells. This new design works well in healthy and damaged hearts.
Clinical trials are already testing this new catheter. In Europe, the CHART-1 clinical trial is presently underway, and this is the first phase 3 trial to examine the regeneration of heart muscle in heart attack patients.
These particular studies are the culmination of years of basic science research at Mayo Clinic and earlier clinical studies with Cardio3 BioSciences and Cardiovascular Centre in Aalst, Belgium, which were conducted between 2009 and 2010. This study, the C-CURE or Cardiopoietic stem Cell therapy in heart failURE study examined 47 patients, (15 control and 32 experimental) who received injections of bone marrow-derived mesenchymal stem cells from their own bone marrow into their heart muscle. Control patients only received standard care. After six months, those patients who received the stem cell treatment showed an increase in heart function and the distance they could walk in six minutes. No adverse effects were observed in the stem cell recipients.
This study established the efficacy of mesenchymal stem cell treatments in heart attack patients. However, other animal and computer studies established the efficacy of this new catheter for injecting heart muscle with stem cells. Hopefully, the results of the CHART-1 study will be available soon.
Postscript: The CHART-2 clinical trial is also starting. See this video about it.
Fat is a rich source of stem cells for regenerative medicine. Treating someone with their own stem cells from their own fat certainly sounds like an attractive option. However, a new study shows that demonstrates that the therapeutic value of fat-based stem cells declines when those cells come from older patients.
“This could restrict the effectiveness of autologous cell therapy using fat, or adipose-derived mesenchymal stromal cells (ADSCs), and require that we test cell material before use and develop ways to pretreat ADSCs from aged patients to enhance their therapeutic potential,” said Anastasia Efimenko, M.D., Ph.D. Dr Efimenko and Nina Dzhoyashvili, M.D., were first authors of the study, which was led by Yelena Parfyonova, M.D., D.Sc., at Lomonosov Moscow State University, Moscow.
Heart disease remains the most common cause of death in most countries. Mesenchymal stromal cells (MSCs) collected from either bone marrow or fat are considered one of the most promising therapeutic agents for regenerating damaged tissue because of their ability to proliferate in culture and differentiate into different cell types. Even more importantly they also have the ability to stimulate the growth of new blood vessels (angiogenesis).
In particular, fat is considered an ideal source for MSCs because it is largely dispensable and the stem cells are easily accessible in large amounts with a minimally invasive procedure. ADSCs have been used in several clinical trials looking at cell therapy for heart conditions, but most of the studies used stem cells from relatively healthy young donors rather than sick, older ones, which are the typical patients who suffer from heart disease.
“We knew that aging and disease itself may negatively affect MSC activities,” Dr. Dzhoyashvili said. “So the aim of our study was to investigate how patient age affects the properties of ADSCs, with special emphasis on their ability to stimulate angiogenesis.”
The Russian team analyzed age-associated changes in ADSCs collected from patients of different age groups, including some patients who suffered from coronary artery disease and some without. The results showed that ADSCs from the older patients in both groups showed some of the characteristics of aging, including shorter telomeres (the caps on the ends of chromosomes that protect them from deterioration), which confirms that ADSCs do age.
“We showed that ADSCs from older patients both with and without coronary artery disease produced significantly less amounts of angiogenesis-stimulating factors compared with the younger patients in the study and their angiogenic capabilities lessened,” Dr. Efimenko concluded. “The results provide new insight into molecular mechanisms underlying the age-related decline of stem cells’ therapeutic potential.”
“These findings are significant because the successful development of cell therapies depends on a thorough understanding of how age may affect the regenerative potential of autologous cells,” said Anthony Atala, M.D., director of the Wake Forest Institute for Regenerative Medicine, and editor of STEM CELLS Translational Medicine, where this research was published.