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Why Fat Tissue? Adipose vs Bone Marrow Stem Cells Explained

Published 2026.10.20 7 min read

Hello, I am Dr. Hidenori Shimada of Grand Green Osaka Umekita Clinic in Osaka, Japan.

If you are researching regenerative medicine in Japan, you may notice that many clinics collect mesenchymal stem cells from fat tissue rather than from bone marrow. International patients often ask why. This article explains, in general terms, the reasoning behind that choice and what to ask a doctor before deciding. It is educational information, not medical advice, and it does not replace a consultation.

The short answer: a practical, general trend

Mesenchymal stem cells (MSCs) are somatic stem cells found in several tissues, including bone marrow and fat. Adipose tissue is generally considered to contain a larger number of these cells per unit of tissue than bone marrow, and collecting fat is usually less burdensome for the patient. These are broad tendencies reported in the scientific literature, not promises about how any individual will respond.

At Grand Green Osaka Umekita Clinic, adipose-derived stem cell therapy is offered as a self-pay (non-insured) regenerative treatment. Whether it is appropriate for you can only be decided by a doctor after a consultation and screening.

What are mesenchymal stem cells?

The human body contains an estimated 37 trillion cells, and old cells are continually replaced by new ones. Stem cells are one source of that renewal. They are defined by two abilities: replicating themselves and differentiating into other cell types.

Mesenchymal stem cells can differentiate into fat, bone and cartilage cells in laboratory conditions. They have also been reported to release anti-inflammatory substances and growth factors that may support the repair of damaged tissue. Research on these properties is active worldwide, and many questions, such as optimal dosing and long-term outcomes, are still being studied.

Fat tissue versus bone marrow: how do they compare?

Both tissues are established sources of MSCs, and both have been used in clinical research. The differences usually discussed are practical ones.

Cell content: fat tissue is generally reported to yield more MSCs per unit than bone marrow, which can matter when cells are cultured and expanded.
Burden of collection: bone marrow aspiration is a more invasive procedure for the body, while fat can be collected through a small incision under local anesthesia.
Amount needed: only a very small amount of fat, roughly a few rice-grain-sized pieces, is needed as the starting material for culture.

It is important to read these points as general trends. Cell quality can vary with a person’s age, health and other factors, and a larger cell count does not by itself mean a better clinical result. Studies comparing the two sources do not all reach the same conclusions, so no single paper should be treated as the final word.

How the treatment flow works with your own cells

In adipose-derived stem cell therapy, a small amount of your own fat is collected on an outpatient basis. The mesenchymal stem cells it contains are then cultured and expanded at a specialized facility, and the cultured cells are returned to your body by intravenous (IV) infusion. Because your own cells are used, this is called an autologous approach, and the risk of rejection is considered lower than with donor cells. Lower does not mean zero, and allergic reactions, infection and other risks still need to be discussed with your doctor.

Culturing takes time, so the process is not completed in a single visit. International patients should ask in advance how many visits are needed, how the schedule can be arranged around travel, and what follow-up is available after returning home.

Safety management under Japanese law

In Japan, regenerative medicine of this kind is provided under the Act on the Safety of Regenerative Medicine, which requires a treatment plan to be submitted and reviewed, and sets standards for cell processing facilities. This framework is designed to support oversight, but it is not a guarantee of results or of freedom from adverse events. Treatment is not covered by public health insurance, so it is a self-pay option, and costs vary by plan.

Before you decide, it is reasonable to ask the clinic to explain which provision plan applies to your treatment, where the cells are processed, and how the clinic responds if a problem occurs.

Questions to ask before you travel to Osaka

A clear list of questions can make a first consultation more productive. Consider raising the following with the doctor.

Why is my own fat considered a suitable cell source in my situation, and are there reasons it might not be?
What are the known risks and possible side effects, and what are the limits of the current evidence?
What is the total cost, how many treatments are planned, and what is not included?
Will my regular doctor receive information about the treatment, and how will follow-up work after I go home?
Does this treatment complement or replace my current care? It should not be viewed as a replacement for standard treatment.

Grand Green Osaka Umekita Clinic, located in Umeda, Osaka, provides an information page for international patients, and you can use it to prepare your questions in advance. Language support and the details of your schedule should be confirmed directly with the clinic.

Key takeaways

Fat tissue is commonly chosen as a source of mesenchymal stem cells because it is generally reported to contain more of them and to be less burdensome to collect than bone marrow. These are general trends, and they do not predict how an individual will respond. Adipose-derived stem cell therapy is a self-pay treatment in Japan that is provided under the regenerative medicine law, and its suitability, risks, side effects and cost must be confirmed through a doctor’s examination. If you are considering it, gather your medical records, write down your questions, and discuss the plan with both your home doctor and the clinic before making any decision.

Fat vs bone marrow cells

Fat tissue

Often reported to yield more cells
Small incision, local anesthesia
Only a tiny amount needed

Bone marrow

Established cell source
More invasive collection
Findings vary between studies

This figure is a conceptual summary of the article content

Learn more about Adipose-Derived Stem Cell Therapy

References

Supervising Physician

Director, Medical Corporation Shimada Clinic
Head of Clinical Practice, Grand Green Osaka Umekita Clinic

Hidenori Shimada

Graduated from the University of Tokushima Faculty of Medicine in 2005. After his initial residency, he obtained U.S. medical certification (ECFMG) and trained as a sub-intern in general surgery at the University of Washington. After completing the doctoral program at Kyoto University Graduate School of Medicine and working as a researcher at the Center for iPS Cell Research and Application (CiRA), Kyoto University, he founded Shimada Clinic in 2013. At Grand Green Osaka Umekita Clinic (https://umekitaclinic.org), he is engaged in a wide range of care, from internal medicine and pediatrics to cell therapy and aesthetic medicine.

* The physician supervision of this article covers its academic content only and does not constitute a recommendation of any specific treatment or product.

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