Is Blood from Bones?

Humans have blood. Without blood, humans cannot survive. Blood is a body fluid that carries oxygen, nutrients and waste products of metabolic reactions occurring in human bodies. Blood is essential for surviving, but do you know where it comes from?

Where blood is formed

Blood cells are formed from the bone marrow by hematopoiesis. Bones are porous as they are filled with soft bone marrow and bone marrow contains stem cells that can differentiate into specific types of cells such as red blood cells, white blood cells, and platelets. These cells travel to the main bloodstream through small capillaries from the bone marrow.

Then how blood cancers are formed?

Blood cancer often occurs in stem cells with genetic mutations. These mutations affect the process of differentiation and form malignant blood cells.

Types of blood cancers

Leukaemia: the number of white blood cells is increased and they live longer than usual. Extra white blood cells fill up spaces that are supposed to be filled with red blood cells and platelets. Moreover, these white blood cells do not function properly.
Lymphoma: Lymphocytes are created more than usual and infection-fighting lymphocytes lose its ability to fight off infections.

Cure for blood cancers

The best cure is to have an allogeneic bone marrow transplant. By replacing a cancerous bone marrow with healthy bone marrow, the body can make healthy blood cells again. Methods for collecting bone marrow and stem cells include:

Peripheral blood stem cell collection or harvest: blood stem cells from the donor's bloodstream are collected by circulating the blood through a machine to separates components. (Need to receive injections of a drug to move stem cells into the bloodstream.)
A needle is inserted into the bone marrow from the hip making this is a painful surgical procedure. Then, skin and bone punctures are needed to get enough bone marrow for a transplant.

Bone marrow transplant

The patient's marrow is destroyed by high doses of chemotherapy or radiation. By this procedure, malignant cells and blood stem cells are destroyed, causing the immune system to weaken as well. Then, the immune system becomes less likely to attack the transplanted cells, allowing the donor cells to be injected into the patient's central line. The cells move to the marrow by chemokines and after a few weeks, healthy blood cells are produced.

The transplant can lead to graft-versus-tumor and graft-versus-host disease.

graft-versus-tumor: new immune cells from the healthy marrow destroy cancer cells
graft-versus-host disease: the immune system that is created by the donor cells attack the patient's organs (30%-50% of patients have this condition). It is important to have the best match of DNA between the donor and the patient.