What are stem cells

An image about parts of stem cell

What are stem cells

The potential of stem cells in multiple therapeutic modalities rivals their ability to turn into almost any specialized cell type as needed. Obtained via a sophisticated, multi-step procedure of aspiration, collection and further processing with specialized equipment, bone marrow harvest and application present a balanced risk-benefit profile with multiple advantages and drawbacks. The stem cells introduced at the injury site lend a much-needed non-surgical hand to natural tissue healing in various orthopedic applications and beyond. Further studies are needed to determine relevant properties of bone marrow and ascertain some aspects of treatment.


Stem cells are undifferentiated cells that have the ability to turn into specialized cell types in human body and not only. Several currently incurable diseases are promised to be treated by them. This includes: orthopedics, cardiovascular dieseases, brain diseases, cell deficiency therapy, blood diseases etc.


Classical classification of stem cells:

-Adult stem cells: Are also known as tissue-specific or somatic cells.Our body has full availability to use them. In gut and bone marrow, stem cells produce new tissues for repair and maintenance.

-Embryonic stem cells: Are  originated from a 4-5 year old blastocyst.Stem cells from embryos are taken through  IVF procedure (in vitro fertilization).The inner cell mass of a blastocyst is where stem cells are found. They have totipotent activity. With proper stimulation, the cells can become blood cells, skin cells etc.

-Mesenchymal stem cells (MSCs): Are originated from stroma or connective tissues that surounds tissues and inner organs.They play a major role in creating bone,fat cells,cartilage and new body tissues.

-Induced pluripotent stem cells (iPS): Laboratory created ,originated by tissue-specific cells and skin cells. Samples of adult tissues or embryo are extracted to produce stem cells. The process of specialization of this stem cells is called direct differentiation.


Types of stem cells due to differentiating ability:


Scientists divide stem cells by their ability to ‘’imitate’’ other body cells.This ability is strongly noticed in embryonic stem cells.They are found in skin,brain,bone marrow,blood and blood vessels,liver.



Totipotent:They have the ability to differentiate into all categories of cells.Th econstruction of zygote is done  by cells with totipotent ability.

Pluripotent: Cells from the early embryothat can turn into any type of cell.

Multipotent: These cells can differentiate into a nearly related family of cells. Example:Adult hematopoietic stem cells, can become platelets, white and red blood cells.

Oligopotent: Cells that can generally  differentiate into different cell types. Adult lymphoid or myeloid stem cells can do this.

Unipotent: These can only produce cells of only one kind, which is their own type. Examples:adult muscle stem cells.

NB! Embryonic stem cells are considered pluripotent instead of totipotent because they cannot become part of the extra-embryonic membranes or the placenta.

Functional heterogenity of Mesenchymal Stem/Stromal Cells and   Cartilage Regeneration is influenced by Bone Marrow-Harvesting techniques

Connective tissue progenitors (CTPs), originated from native bone marrow (BM) referred to mesenchymal/stromal cells are highly promising for treatment of cartilage injuries. However,the cartilage regeneration capacity still remains questionable because of cell heterogenity.

             Methods for preparation:

BM aspiration and BM collection are the 2 main techniques used for patients to undergo total hip replacement. Immunochemistry verified the spastial localization  of various CTP subsets in BM.

The harvest techniques of BM indicates the efficiency of cartilage construction.

Bone marrow aspiration

The procedure that involves taking a sample of the liquid part of the soft tissue inside our bones. It can be performed in case of bone examination and diagnostic purposes.

Related disease include:

  • anemia
  • myelofibrosis or myelodysplastic syndrome
  • leukopenia or polycythemia vera
  • hemochromatosis
  • tuberculosis
  • storage diseases, such as amyloidoses or Gaucher’s disease


1-Palpation and location of the PSIS.

2-Puncture;Incision and insertion of the aspiration needle to the bone.

3-Angle;the 40 0 angle is aimed during the help of fluoroscopy aiming toward the tear drop.

4-Advance:the needle advances between the tables of posterior iliac crest.

5-Aspiration:We remove the stylet and connect it with a syringe. We rotate the needle and aspirate simultaneously.

6-Adjust:We replace the stylet and reposition the  needle. The last 2 procedures are repeated 5-6 times in order to receive the desired total bone marrow.

Bone marrow aspirate concentrate

Bone marrow concentrate (BMC) uses stem cells that are harvested from your own bone marrow to help the body heal on its own. These cells, when injected directly into an injury site, empower a rapid and efficient restoration of the tissue, returning it to a more healthy state by stimulating the body’s own natural healing response. It is a promising, non-surgical treatment for various orthopedic injuries, including mild to moderate osteoarthritis, disc degeneration and soft tissue damage.

Advantages and Disadvantages of Bone Marrow Aspiration Harvest and Application





Technically easy to harvest Potential pain during harvest with local anesthetic alone
No culture expansion Variable stem cell quantity and quality depending on age
No risk of allogeneic disease transmission Potentially detrimental effect of erythrocytes when used in intra-articular environment
Low risk of infection
May be performed with concomitant procedure



Clinical case and orthopedic application:

Nucleated cells of bone marrow samples in the anterior iliac crest of thirty-two patients, free from systematic diseases, were taken under evaluation. The concentration of the osteoblast progenitor cells also were determined, by storing the bone-marrowderived cells into tissue-culture medium and calculating the number of alkaline phosphatase positive colony-forming units.2 experiments were conducted in order to evaluate the effect of aspiration volume.First’s experiment purpose was to compare the volume of 1 and 2 milliliters volume. In second experiment, 2 and 4 milliliters volume was compared.

Clinical Significance:

Not greater than 2 milliliters should be the volume of aspiration of bone marrow used as a bone graft. A higher volume minimizes the concentration of osteoblast progenitor cells because of dilution  of peripheral blood with bone marrow samples. We confirm that  four one-milliliter aspirates will provide almost twice the number of alkaline phosphatase-positive colony-forming units as will  one-four millimeter aspirate.


Humans differ significantly from one another due to cellularity of bone marrow and the expansion of the osteoblast progenitor cells. Further studies are needed  to determine the prevalence of alkaline phosphatase-positive colony-forming units in bone marrow.


  1. Brazier, Y. (2018). What are stem cells, and what do they do?. [online] Medical News Today. Available at: https://www.medicalnewstoday.com/articles/323343.php [Accessed 1 Jul. 2019].
  2. Sivasubramaniyan, K., Ilas, D. C., Harichandan, A., Bos, P. K., Santos, D. L., de Zwart, P., … van Osch, G. J. V. M. (2018). Bone Marrow-Harvesting Technique Influences Functional Heterogeneity of Mesenchymal Stem/Stromal Cells and Cartilage Regeneration. The American Journal of Sports Medicine, 46(14), 3521–3531. https://doi.org/10.1177/0363546518804807
  3. What is a Bone Marrow Aspiration and Biopsy?. (2019). Retrieved from https://www.webmd.com/a-to-z-guides/bone-marrow-aspiration-biopsy#1
  4. Krans, B. (2018). Bone Marrow Aspiration. [online] Healthline. Available at: https://www.healthline.com/health/bone-marrow-aspiration#purpose [Accessed 1 Jul. 2019].
  5. Muschler, G. F., Boehm, C., & Easley, K. (1997). Aspiration to Obtain Osteoblast Progenitor Cells from Human Bone Marrow. The Journal of Bone and Joint Surgery (American Volume), 79(11), 1699–1709. https://doi.org/10.2106/00004623-199711000-00012
  6. Rahman, R. (2017). BONE MARROW ASPIRATION GUIDE. [online] Available at: https://assets.website-files.com/59e38f95ec229e00016e0ebd/5b2b8cdf591dcb548236e814_BMA%20Technique%20Guide_17-1093-2.pdf [Accessed 1 Jul. 2019].

Leave a Comment

Your email address will not be published. Required fields are marked *

Choose language »