Human Cartilage can be 3D-printed

We’ve already discussed about the importance of cartilages in the human body. Two examples are the knee menisci and the thyroid cartilage that origins the Adam’s apple. We’ve also understood that 3D printing would probably represent a great revolution in the world of medicine, with the possibility of reproducing human body parts or fabricating new-generation assistive tools. Put the two things together and you’ll be able to print human cartilage by means of a 3D printer. I simply copy-paste here the content of this interesting webpage (to which all rights belong).

Dr. Darryl D’Lima and the members of his team at the Scripps Clinic in La Jolla, California, say they’ve unlocked the secrets of bioprinting human cartilage. That’s big news as the current best practice medical technique to replace lost cartilage is implantation of an artificial joint. Even though that sort of operation is painful, requires a long stretch of rehabilitation and artificial joints can often need replacement as time goes on, such procedures are the industry standard.

The global market for knee replacements amounts to nearly $7 billion annually, and experts say it will climb to nearly $11 billion within the next few years. Somewhere around 773,000 Americans have a hip or knee replaced each year. That’s big business and a lot of pain. But D’Lima says the design of his latest prototype bioprinter will print living cartilage, and that would mark a great leap forward for those suffering from painful knee and joint damage. Taking a Hewlett-Packard inkjet printer as his starting point, D’Lima says his bioprinter uses cartilage progenitor cells suspended in a biocompatible liquid. Once the solution is exposed to ultraviolet light, it takes a permanent shape.

The extremely tiny drops of material provide other benefits as well. Measuring just one picoliter in diameter (or one-billionth of a liter), the droplets output by the bioprinter are compact enough to fill microscopic pits on the surface of cartilage or bone. “It would be the equivalent of filling a pothole,” D’Lima says. “It would automatically fill the defect as you’re printing it. You’re getting a fairly good mechanical integration into the tissue, which is very difficult for us to do when we do traditional transplants.”

Patients suffering with arthritis or  knee injuries are often plagued by a lack of cartilage. That means bones begin to grind against bones, and that means extreme pain and constant discomfort for patients. Using D’Lima’s bioprinting method, cartilage can be applied directly into the knee joint to provide a custom fit impossible to achieve by cutting pre-made cartilage to the particular patient. And one day, D’Lima says he’s confident that the process will involve printing the cartilage material directly onto a patient on the operating table. “We wouldn’t have to prepare (material) in advance,” D’Lima said. “All of this would be done on the day of surgery, on demand.”

The major hurdle, according to D’Lima, is that as there’s currently no printer which can print directly onto a patient. His technique needs some refining. D’Lima says he’s working on those tweaks now with biotech firms Invetech and Organovo. And D’Lima also says he’s certain the method will work in practice as cartilage, due to its simpler cellular structure and lack of a complicated network of blood vessels, will be less challenging to create than some other tissues. Cartilage, flexible connective tissue found in various areas of the body, is not as rigid as bone but can be stiffer and less flexible than muscle. Composed of specialized cells called Chondrocytes, cartilage (unlike other connective tissues) doesn’t contain blood vessels. The chondrocytes are supplied with nutrients by diffusion as a result of the pumping action generated by compression, so in comparison with other connective tissues, cartilage grows and repairs much more slowly. “(Cartilage) is complex enough that you need technology like 3D printing, but at the same time, it’s not so complex that it’s extremely challenging,” he said. “We’ve gotten interest from other researchers, wanting to print retinal cells. The retina has some similarities to cartilage in that the photoreceptors and the neural cells of the retina don’t require a blood supply, so we don’t have to print microvasculature. And the retina is a mature tissue in that if you lose a photoreceptor, that’s it. You don’t grow a new one. So it’s fairly attractive for 3D printing.”

Gender Equality & Adam’s Apple

Even if in the 4th century BC Aristotle firmly believed that women were inferior to men (he defined them some kind of subordinate, deformed male, unfinished man… a friendly buddy this Aristotle, wasn’t he?), we all know this is not true. Most guys (myself included, for sure) are hopeless cases for like doing the ironing or properly folding a shirt… but this doesn’t justify any ranking between genders 🙂

Despite this, nowadays many people keep a sexist attitude and male chauvinists find it funny to look for differences between man and woman. Since such people are usually very clever (…), they may endorse their opinions by pointing out things that men have and women don’t. One of the most cited ones is the Adam’s Apple, typical of men and absent in women’s neck. But… wait! Apparently this is not true 🙂

The Adam’s apple is technically known as the laryngeal prominence and is present in both men and women. The trick is just that this prominence is more visible in men than in women. Inside the human neck there is the larynx, an awesome voice box that houses the vocal chords and manipulates the volume and the pitch of our voice. The larynx and the trachea, which is located just below, are protected by a host of cartilages layers that serve as a protection for the vocal chords and as an attachment for several laryngeal muscles. The largest of these layers is the thyroid cartilage, which is positioned externally and forms the laryngeal skeleton. The thyroid cartilage has a sort of protrusion where the two anterior cartilage laminae meet and fuse: it’s the Adam Apple. The shape of such bump is an acute angle (about 90°) in men and an open arc (about 120°) in women. That’s why the Adam’s Apple is usually clearly visible and palpable in men, while it’s hardly perceived in women.

Girls and boys are born with similarly sized thyroid cartilage. During puberty, the boys’ testosterone levels increase and their voices change. This causes a development of their Adam’s Apples, which become noticeably bigger and make their voices change. Grown men have larger voice boxes, speak in deeper tones than women and usually have more prominent Adam’s Apples.

As we can learn from this website, the origins of the term Adam’s Apple “go all the way back to the Biblical event where Eve gave Adam a forbidden fruit (from the tree of Knowledge of Good and Evil), which is commonly misrepresented as an apple.  The term then basically comes from the legend that when he ate the apple, the piece got stuck in his throat and made a lump“. Then they got banished from the Garden and we all know the story… And that, kids, is how we ran into male chauvinists!

sources: one, two, three

the Knee Bursae: some hints

The bursae of the knee can be defined in a very simple way: they are fluid sacs, or synovial pockets. This second definition comes from the sinovial fluid that fills them.

Synovial fluid is made of hyaluronic acid and lubricin, proteinases and collagenases. Its main functions are reducing friction by lubricating the joint, absorbing shocks and properly “feeding” joint cartilage. In the case of the knee, the Knee Capsule encloses the Knee Cavity which is filled with synovial fluid. Knee Bursae surround and sometimes communicate with the Knee Cavity, as we can see in the picture.

Usually Knee Bursae are thin-walled and represent the weak point of the joint. At the same time, their presence is really important since they enlarge the joint space. They can be grouped according to:

• their characterization as communicating and non-communicating bursae. A communicating bursa is when a bursa is located adjacent to a joint, thus having the synovial membrane in communication with the joint itself.
• their location (frontal, lateral, medial).

In pathological conditions, such as excessive local friction, infection, arthritides or direct trauma, fluid and debris collect within the bursa or fluid extends into the bursa from the adjacent joint. As a consequence, the walls of the bursa thicken as the bursal inflammation becomes longstanding. The term bursitis refers to pathological enlargement of the bursa. Clinically, bursitis mimics several peripheral joint and muscle abnormalities.

   

<–prepatellar bursitis

          elbow bursitis–>

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sources: Wikipedia and this website

the Meniscus: some hints

Medically speaking, the “cartilage” is actually known as the meniscus. The meniscus is a C-shaped piece of fibrocartilage which is located at the peripheral aspect of the joint. The majority of the meniscus has no blood supply. For that reason, when damaged, the meniscus is unable to undergo the normal healing process that occurs in most of the rest of the body. In addition, with age, the meniscus begins to deteriorate, often developing degenerative tears. Typically, when the meniscus is damaged, the torn piece begins to move in an abnormal fashion inside the joint.

Because the space between the bones of the joint is very small, as the abnormally mobile piece of meniscal tissue (meniscal fragment) moves, it may become caught between the bones of the joint (femur and tibia). When this happens, the knee becomes painful, swollen, and difficult to move.

The meniscus has several functions:

• Stability – As secondary stabilizers, the intact meniscii interact with the stabilizing function of the ligaments and are most effective when the surrounding ligaments are intact.

• Lubrication and nutrition – The meniscii act as spacers between the femur and the tibia. By doing so, they prevent friction between these two bones and allow for the diffusion of the normal joint fluid and its nutrients into the tissue which covers the end of the bone. This tissue is known as articular cartilage. Maintenance of the integrity of the articular cartilage is critical to preventing the development of post-traumatic or degenerative arthritis.

• Shock absorption – The biconcave C-shaped pieces of tissue known as meniscii (cartilage in non-medical terms) lower the stress applied to the articular cartilage, and thereby have a role in preventing the development of degenerative arthritis.

source: this website