Tag Archives: regenerative medicine

Bioengineered ACL

New Bioengineered ACL May Provide Optimal Treatment for Torn ACLs

Researchers at Northwestern University have developed artificial anterior cruciate ligaments, better known as ACLs, to replace torn ligaments—a common sports injury. The bioengineered ACLs are made from braided polyester fibers, which are comparable in tensile strength to the actual ACL, and thus capable of stabilizing the knee.

ACLs connect the femur (thigh bone) to the tibia (the larger of the two leg bones). Once an ACL is ruptured or completely torn, it does not heal, mainly because it’s an intra-articular ligament that’s located within the knee joint. When extra-articular joints are injured, like the medial collateral ligament (MCL), they have the ability to repair itself with rest. A blood clot forms, which serves as the bridge to connect the tear to the bone, and healthy tissue grows to replace the gap. Within the knee joint, any clots that form get washed away with the constant influx of synovial fluid, inhibiting ACLs from being healed.

Conventional treatment for a torn ACL is reconstructive surgery using grafts from the patellar tendon (kneecap). Resulting surgery can cause lasting soreness and tenderness and permanently weaken the patellar tendon. In some cases, the weakened tendon may rupture completely. Even without any major complications and years of physical therapy, natural ease of movement is never fully achieved.

Using rabbit models, the scientists drilled holes into the femur and tibia. Prior to inserting the bioengineered ACL into each receiving end, the fibers were first dipped into a concoction of hydroxyapatite (calcium derivatives naturally found in teeth and bones) nanocrystals and a porous antioxidant biomaterial. Upon anchoring the ends, the rabbits’ nearby bone and tissue cells began to resettle into the pores of the mixture. The researchers hope the ends of the bioengineered ACL can be fully integrated into the femur and tibia given enough time.

The prospect of incorporating an artificial bioengineered ACL to natural bone is promising news for the scientists. However, more studies need to be conducted before human trials begin.

New Nerve Allograft Repair Method

New Nerve Allograft Repair Method to Mend Severed Nerves

In the human body, and in most mammals, minor peripheral nerve injuries are repaired autonomously and don’t require surgical intervention. However, traumatic nerve injuries, such as gunshot wounds, saw and tractor injuries—often the kind where the nerve is not severed cleanly—usually result in a “hole” in the nerve and require a filler to ensure proper nerve regeneration. Physicians at the University of Kentucky’s (UK) Hand Surgery Service have developed a new nerve allograft repair method to help mend broken nerves that appear to be more promising than conventional methods.

To patch the holes in nerves, surgeons traditionally use nerve autografts and nerve conduits. In the former technique, two severed nerves are connected using the patient’s own nerve taken from somewhere else in the body, resulting in nerve loss and sensation at donor site. In the second approach, synthetic tubes are used to bridge the damaged nerves. The latter method can increase the risk of infections, and a patient also runs the risk of developing an allergic reaction to the material used to manufacture the nerve conduit.

The new nerve allograft repair method uses nerves cultivated from human cadavers which are processed to remove cellular debris while retaining the nervous structure. When compared with patients who underwent the nerve conduit procedure, patients who had the nerve allograft repair method performed better on sensory and motor tasks while avoiding allergic reactions and infections.

Currently, all three nerve repair methods rely on the body’s natural physiologic reserve to reconstruct damaged nerves once the gaps are filled, which can take a long time for the nerve to regenerate depending on a person’s age and comorbidities. UK scientists are working on incorporating growth factors to nerve allografts that would aid nerve regeneration and decrease recovery time, thereby improving nerve allograft repair method results.

First Transfusion with Artificial Blood Not Far Off

The Scottish National Blood Transfusion Service (SNBTS), in conjunction with various other medical research institutions in the United Kingdom and Ireland, have created artificial blood in the form of type O negative, otherwise known as the “universal donor,” a rare blood type that all other blood types can receive without the potential of severe, life-threatening immunological reactions occurring. The first transfusion with the new artificial blood is expected to occur late 2016.

Artificial blood, namely red blood cells, are produced by dedifferentiating fibroblasts—cells that generate connective tissue in the body, such as blood, bone, and cartilage—from an adult donor and reprogramming them into induced pluripotent stem cells (iPSCs). The iPSCs are then cultured for a month in a bone marrow-like environment, where mature red blood cells with their characteristic lack of nuclei are extracted.

Currently, non-blood volume expanders are available as an alternative to blood transfusions, which serves as a viable option for patients who have certain religious beliefs, such as Jehovah witnesses, who cannot accept animal products. Dextran, hetastarch, pentastarch, and normal saline or Lactated Ringer’s solution can be used to maintain blood volume and pressure. But they do not increase the blood’s oxygen-carrying capacity, which is the sole responsibility of red blood cells—namely hemoglobin, a metalloprotein that contains iron.

Even though 107 million blood donations are collected annually, according to the World Health Organization (WHO), blood is still in demand, particularly in developing nations. And despite of strict regulations regarding blood collection, storage, and release of its use, the risk of incompatibility reactions and transmitting diseases to recipients still exist.

With artificial blood, the constant need for blood donations is addressed, along with not worrying about infecting a patient with contaminated blood or other potential adverse reactions. Artificial blood is also a culturally sensitive solution to blood loss.

Functional Bioengineered Vaginas

Medical scientists recently announced the indelible success of bioengineered vaginas that were implanted into four teenage girls—a first in the ever-expanding field of regenerative medicine. The research project was led by a physician from Wake Forest Baptist Medical Center’s Institute of Regenerative Medicine in North Carolina.

The subjects were females between 13 and 18 years of age who were born with Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome, a rare genetic condition that only affects newborn girls in which the uterus and vagina are underdeveloped or entirely absent. The bioengineered vaginas, derived from the patients’ own muscle and epithelial cells which were sampled from their external genitalias, were surgically implanted between June 2005 and October 2008.

The extracted cells were expanded, or cultured to replicate, and placed on a biodegradable “scaffold” that’s been hand-shaped into a vagina-like structure tailored to the individual subject. Approximately 5-6 weeks after cells were extracted from patients, the seeded scaffolds are sewn into patients’ pelvis where a man-made canal was dug. Nerves and blood vessels form and the scaffold cell seeds proliferate into tissue. As the scaffold is absorbed into the body, the cells continue to expand to lay down a permanent support structure that will become the new “organic” vagina.

Based on yearly follow-up visits, MRI scans, tissue biopsies, and internal exams using magnification equipment, the bioengineered vaginas were more or less indistinguishable in form and function to native tissue. Moreover, the subjects’ answers to the Female Sexual Function Index questionnaire revealed they had normal sexual function after surgery, including desire, arousal, and pain-free intercourse.

Current treatments for MHRK syndrome involve dilating existing vaginal tissue or vaginal reconstructive surgery. Skin grafts or abdominal tissue are usually used for the reconstruction but they lack muscle and the new vaginal graft has a tendency to narrow or contract which then requires dilation.

With more clinical experience and an established surgery protocol, the team is hoping to expand the application of implanted bioengineered vaginas to patients with vaginal cancer or incurred vaginal trauma injuries.