TeachableMedicalNews article  04012020

Teachable moment in classrooms:

  1. cellular basis of life chapter – concept of one gene, one protein
  2. cellular basis of life chapter – concept of gene mutation leading to protein malfunction
  3. cellular basis of life chapter – adhesion proteins in plasma membrane
  4. blood chapter – red blood cell structure
  5. blood chapter – sickle cell anemia caused by globin gene mutation

The news item:  Recently a new drug, Adakveo, was approved to treat sickle cell anemia patients:

https://www.cnbc.com/2019/12/20/novartis-wins-medicaid-approval-for-new-sickle-cell-drug-in-key-us-states.html

The article mentions that this disorder afflicts 100,000 people in the USA, that the disorder is caused by sickle shaped red blood cell, that the drug is a biological and injectable drug, and that the drug treats the pain crises of this disorder.

So, Why Do I Care??  There are millions of people living with this disease worldwide. In less developed countries many children die before reaching the age of 5.  The disease comes with painful episodes called pain crises, and with many additional complications such as anemia, musculoskeletal and neurological problems. The drug in the article reduces the numbers of pain crises.

Plain English, Please!!!  First, let’s talk about the mutation that causes sickle cell anemia. The shape of the sickle red blood cells is like a crescent moon, or a pointy-ended football.  Mutated hemoglobin, the protein inside the red blood cell, is causing that abnormal shape.  The mutation changes a single amino acid in the globin part of hemoglobin. The mutated hemoglobin aggregates into large chunks, and those chunks deform the shape of the entire cell.

Second, let’s talk about what’s causing the pain crises.  The sickle shape changes what red blood cells do inside blood vessels.  As blood flows, normal red blood cells bounce off the side of blood vessels, but sickle red blood cells land on blood vessel walls like a pancake.  So, the sickle red blood cells get stuck very easy in small blood vessels. When red blood cells pile up inside blood vessels, then blood cannot flow past the obstruction.  When blood doesn’t flow, then the cells are starved for oxygen and nutrients, and the stressed cells release chemicals that cause pain in muscles, bones and joints.

Third, let’s talk about how we can make sickle red blood cells less sticky.  The sickle red blood cells stick to  the blood vessel wall just like Velcro. One part of the Velcro are adhesion molecules on the cells of blood vessel wall, and the other part of the Velcro are molecules on red blood cells. When those two parts make contact, the sickle red blood cell is stuck.  How could we block this Velcro/adhesion system? How about putting something in between the two parts of the Velcro?  The new drug, Adakveo, covers up the adhesion molecules on blood vessel walls, so the molecules on the sickle red blood cells cannot contact the other part of the Velcro, so there is no sticking, thus blood flow remain normal, and pain is not produced.

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