MODERN THERAPEUTIC BLOODLETTING
As was the case with Galen’s views on the
source of BLOOD, there is also a fragment of
validity in the practice of bloodletting. Contem-
porary physicians use modern variations of this
ancient practice to treat several conditions. Ther-
apeutic PHLEBOTOMY withdraws blood to treat
HEMOCHROMATOSIS, in which the blood contains
too much iron. Therapeutic HEMAPHERESISselec-
tively extracts components of the blood and
returns the remainder to the individual, such as
to treat SICKLE CELL DISEASE.In 1628 British physician William Harvey
(1578–1657) refuted Galen’s pronouncement with
his published evidence of the blood’s circulation
through a closed network of arteries and veins,
establishing the recognition of the blood as a finite
composition within the body. Within 20 years
physicians began experimenting with BLOOD TRANS-
FUSION, though what was to become a lifesaving
mainstay of medical treatment did not become
practical until the early 1900s. Karl Landsteiner
(1868–1943), an Austrian-American immunolo-
gist, was the first researcher to identify the poly-
saccharides on the surface of erythrocytes (red
blood cells) that were to become known as blood
types. The discovery at last explained why one
person’s blood could harm another person and
made possible the therapeutic use of drawing
blood from one person for transfusion into
another person. Landsteiner won the 1930 Nobel
Prize in medicine or physiology for his work, and
by the 1950s blood transfusions were standard
therapy for a wide range of health conditions.
Transfused blood became a notorious vehicle of
death in the early 1980s with the eruption of
HIV/AIDSin Western populations. Though scientists
had long known of blood’s ability to transmit
infections such as MALARIAandHEPATITIS, this new
VIRUSbecame a particularly lethal threat for people
who relied on chronic blood transfusions to treat
health conditions such as hemophilia and sickle
cell anemia. It also raised ethical dilemmas in situ-
ations of massive trauma in which the only treat-
ment was equally massive transfusions of blood.
Thousands of people acquired HIV/AIDS from
blood and blood products until reliable screening
procedures and testing for the presence of HIV in
donor blood became available in the late 1990s.Breakthrough Research and Treatment Advances
Among the most significant breakthroughs in
treatment advances are therapies for cancers of
the blood, bone marrow, and lymphatic tissues.
Complex CHEMOTHERAPY regimens, bone marrow
transplantation, and peripheral blood stem cell
(PBSC) transplantation can turn some leukemias
from fatal to long-term REMISSIONor cure. About
80 percent of children under age 14 who undergo
treatment for acute lymphatic leukemia (ALL), for
example, experience complete and apparently
permanent remission such that doctors are willing
to call them cured.
Much current research centers on blood stem
cells, with scientists searching for ways to encour-
age these pluripotent cells to differentiate into
cells of types other than blood cells. Peripheral
blood stem cells share many of the characteristics
of their omnipotent counterparts, embryonic STEM
CELLS, including the ability to either replicate
themselves or differentiate into specific cell types,
and are easy to collect via extraction from BLOOD
DONATION or HEMAPHERESIS. Though these efforts
have so far met with limited success, they have
resulted in new understanding of the complexities
that underlie cell differentiation and proliferation
in both health and disease.122 The Blood and Lymph