Two Opposing Models?

The medical profession has historically operated with the model that health can be achieved solely as a series of biochemical reactions. “Better living through chemistry” is a common quote that can be found in relation to this. Historically, osteopathic physicians (D.O.’s) have been attacked and dismissed for practicing “manual medicine.” D.O.’s argued that they operate on a different aspect of health by optimizing the structure. Critics have complained that there is “no evidence” for this model.

Science is showing more and more the plausibility of this in other fields besides osteopathy. The goal with this article is to show that looking at biochemistry or manual medicine alone as being mutually exclusive from each other are incomplete models that don’t serve the patients. Research is showing that both go hand in hand because in fact mechanical forces do affect the biochemistry by altering the gene expression in the body.

The Opposing Arguments

One of the common arguments against the cranial osteopathy model is that the sutures “fuse” and motion between them is impossible. In the cranial osteopathy model, the bones do not fuse. Furthermore proponents argue there is a constant motion that is not only possible, but constantly takes place at the sutures. It has long been known that dura mater, a specialized membrane in the skull and the spinal canal, exits through the sutures in the skull. This is where the bones come together as they close in development. An important question to ask is “how can there be complete fusion if there are membranes exiting through those sutures?” Let’s dig a little deeper and look at the the anatomy and science here that supports the potential for motion at the sutures.





Stem Cells In the Sutures?

The cranial bones in a skull can be disarticulated, separated at the sutures, fairly easily by filling up the inside with rice and water. As the rice expands, it separates the bones at the sutures with each bone consistently retaining its shape. Looking more closely, scientists have long known that stem cells reside in the bone marrow of long bones. The bones of the head develop differently and where the stem cells reside in these bones has not been well understood.

The bones of the skull cap, calvarial bones, develop through a process called intramembranous ossification. In a study titled “Calvarial Suture-Derived Stem Cells and Their Contribution to Cranial Bone Repair,” the researchers identified a major stem cell population within the sutural mesenchyme. These stem cells have multiple differentiating abilities and intrinsic reparative potential. Another interesting factor is that sutural growth is controlled by signaling from the dura mater and through the periosteum, a membrane covering the outer surface of the bones. We’ll discuss more and more why that’s important. For now, the important take away point is that there are stem cells within the dura mater within the sutures of the skull.

Activating Stem Cells

But what factors trigger the stem cells to activate bone growth? Researchers in another study titled “Mind the Gap: Genetic Manipulation of Basicranial Growth within Synchondroses Modulates Calvarial and Facial Shape in Mice through Epigenetic Interactions” showed that mesenchymal stem cells respond strongly to mechanical stimuli. They studied the epigenetics of craniofacial development finding that the phenotypic expression changes with inhibition to cartilage growth within synchondrosis. What this means in layman’s terms is that inhibiting the growth at certain sutures during development would also have an effect on how the rest of the head would develop.

They found that the stem cells in the sutures respond to different kinds of forces such as tension, compression, and fluid-induced shear. The stem cells are reacting to the mechanical forces around them and that is a strong factor in stem cell differentiation and growth. This answers in explaining what is happening with cranial synostosis, a disease where certain sutures are considered to fuse prematurely, may lie here because rather than premature fusing, this may be a result of stem cell over activation for unclear reasons.

The authors stated, “Mesenchymal stem cells have also been shown to be highly mechanosensitive and this may present an ideal method for controlling mesenchymal stem cell differentiation.”

So the question becomes, “If motion at the sutures is impossible, then why have stem cells that respond to mechanical forces?” It has been theorized that stem cells are mechanosensitive because a trauma will immediately activate them to start differentiating and growing for healing.

A “Mater” of Motion

The idea that stem cells respond to mechanical forces suggests the possibility for movement at the sutures, but also suggests motion at the dura mater, specialized membranes within the skull and spinal canal, because that’s where the stem cells reside. Because dura mater is attached to the bones of the skull, movement within the bones can pull and tug or put slack throughout different parts of the dura mater affecting stem cell activation. Motion at the dura mater is also consistent with what cranial osteopathic physicians have been arguing for many decades. The recent discovery of lymphatic vessels that primarily reside in the dura mater also suggest motion.

Osteopathic physicians have for decades described a constant motion at the dura mater calling it “reciprocal tension membranes.” This means when one part has tension on it, another portion will have slack. It will go back and forth like a pendulum. In addition to the stem cells at the dura that respond to mechanical forces, a recent study titled “Human and nonhuman primate meninges harbor lymphatic vessels that can be visualized noninvasively by MRI” reinforces the idea that there is motion at the dura mater.

In the body, the lymphatics rely partially on the motion of the musculoskeletal system. Contraction of muscles will help move lymphatic fluid through the lymphatic vessels. In the head, however, that cannot be the case. Until very recently, lymphatic vessels were not thought to be present in the cranium. Therefore in order to move the lymphatic fluid through in the skull, it would make sense to embed the vessels in a structure that is constantly fluctuating with motion.

Mechanical Forces Altering Gene Expression?

Looking deeper into this, research has also answered the question of how mechanical forces can trigger differentiation or gene expression of particular cells. The answer lies in another study titled “Transcription upregulation via force-induced direct stretching of chromatin.” The scientists in this study found that external forces can directly regulate gene expression and affect cell behavior. This means that an outside force can activate or inhibit a certain portion of DNA.

They showed a direct pathway from the cell cytoskeleton attached directly into the nucleus of the cell onto the DNA. An external force directly causes regions of chromatin (condensed DNA and protein mixture that makes up DNA) in the cell nucleus to stretch out. The stretching out of the chromatin then increases transcription of the genes in the stretched regions.

The amount of gene expression and chromatin stretching depends on the direction of force on the cell’s cytoskeleton. The prior sentence is important because it does also provide an explanation as to why there is much variability in the effects of manual work. The direction and likely the amount of force introduced by a practitioner with their hands can be the difference between triggering an effective change or not producing the desired result.

Evidence of Cranial Bone Motion?

This information is interesting but it does not show that the sutures can be manually affected to produce changes. Some of the research, outside of the osteopathic field, has been done in the field of dentistry. Dr. Dave Singh of a company called Vivos has published approximately 200 studies and is the creator of an appliance called the DNA appliance. As I understand it, the purpose of this appliance is to remodel the roof of the mouth and face to remodel the airway for obstructive sleep apnea and other sleeping disorders. This appliance is unique in that it is not worn all the time, primarily at night, and it is not painful because not a lot of force is used.

Gentle Forces Making Big Changes

Why does it not take a lot of force? Critics of cranial osteopathy suggest that it would be impossible to move the sutures with little force. The answer as to whether this is possible or not lies in growth and development. The forces acting on growth and development activating growth are not in most cases aggressive, painful, or triggering a lot of inflammation. The forces of growth do not trigger a strong inflammatory response. Growing is not generally a painful process. That is the principle that the DNA appliance works with. It induces a gentle stretch at the sutures to trigger activity. This can be a reason is why the releases from cranial osteopathic physicians on the sutures, or the rest of the body for that matter, may not require much force to be effective.

Furthermore, an end point of a release has been described as a “fluid fluctuation” at the site of release felt like a pulsation. Recalling from above, one of the forces that activates gene expression is “fluid induced shear.” This is pressure acting on a cell from fluid traveling over a cell. An example of this would be the cells lining the blood vessels affected by the fluid tat passes over them. During a release, feeling a fluid fluctuation into the area may be restoring a fluid induced shear that triggers changes the gene expression of an area.

DNA Appliance

Going back to the DNA appliance, the reason the appliance is worn at night is because growth hormone is released during deep sleep cycles and amplifying the ability of the appliance to trigger bone growth. The workings of the appliance is based on the concepts above of providing a gentle stretch to trigger gene expression and restore a person’s craniofacial development and airway closer to how it was meant to have developed under normal circumstances.

This can be accomplished in children and adults. Using a cone beam scanner, Dr. Singh has measured changes in palate expansion over time to several millimeters and bone growth. If motion between the bones was not possible, then the appliance would not work, as even a gentle stretch is motion. Nor does it work by brute force like other methods, such as braces, do. In addition to this, 3D models of airways before and after treatment show the success of the appliance having an effect on the airway, nasal cavity, and hard palate using a gentle, nonsurgical, and drug free manner. In many cases, patients have been able to wean off of a CPAP device for obstructive sleep apnea.

None of this would be possible if if the capacity for motion at the sutures was not there. What we have learned recently is the effects of mechanical forces on affecting the overall functions of the tissues down to the level of the genes. We have a lot of studies showing that the biochemistry of the body can be altered, but understanding the role the mechanical forces play are not as clearly understood. Harnessing mechanical forces to make changes is not accomplished as easily as creating a drug. The more and more we understand how the two models work, the less separated the biochemical and mechanical models of medicine appear to be. Then, the true power of medicine could really be achieved.

Hopefully osteopathic physicians practicing cranial osteopathy can start implementing the use of these 3D technologies to start measuring and demonstrating the changes that are taking place.