From Alzheimer’s to Zebrafish: Eclectic Science and Regulatory Stories 18
as devices by virtue of their mechanical effects of chewing and removing dead tissue. The
predicate devices included scalpels and maggots sold by Lederle Laboratories.
Sherman believes that the device classification was one of convenience, as maggots
also produce substances that kill bacteria and stimulate the growth of healthy tissue.
Proving these effects would be more difficult, however, as the documentation and meth-
odology would be extremely rigorous and time consuming. On his website, Sherman
provides a detailed description of how to make a wound dressing.9 He also published
information in two articles in 1996 and 1997.10,11 It is of interest that Sherman found that
80% of maggot-treated wounds had all dead tissue removed, compared with just 48% of
wounds that are surgically debrided. Maggot-treated patients may also spend fewer days
on an antibiotic regimen.
Leeches
Leeches are closely related to earthworms and lugworms. They thrive in mountain lakes,
desert oases and even polar oceans. There are 650 known species, and unlike other worms,
leeches have a sucker at each end, one for feeding and one for hanging on. The medicinal
leech (Hirudo medicinalis) has three jaws with 100 teeth in each. The specific value of leech
therapy is related to the properties of its bite. Leeches secrete hirudin, a direct thrombin
inhibitor.12 Other substances produced by leeches include a vasodilator, hyaluronidase,
and an anesthetic.13 Hyaluronidase is an enzyme that increases the permeability of leech
saliva through human tissue and also exhibits antibiotic properties. The leech is also
unique in that its digestive tract contains a single bacterial species, Aeromonas veronii. This
organism may inhibit the proliferation of other bacteria.
Although only cleared by FDA in 2004, the medicinal leech has been used for eons,
even earlier than maggots. Their use was first recorded in 200 BC, and according to
historians, such therapy began even earlier in India.14 In the Napoleonic era, the Empress
Josephine was treated with leeches after a fall. Napoleon’s military surgeon advocated
using 30 to 50 leeches at a time, enough to draw up to 1-1/2 quarts of blood.15 (Leeches
can consume more than five times their body weight.) At that time, it was estimated than
more than 40 million leeches were used annually in France.16 In the late 1800s, leeching
became so popular that the common preferred variety became an endangered species.
The great advantage was that leeches could extract blood with very little pain and could
be used on almost any part of the body. By the early part of the 20th century, however, the
use of leeches in medical treatment was in steep decline.
Rediscovery and Regulatory Issues
The late 20th century saw a renewed interest in leeches by both the lay and scientific
communities. This stemmed from clinical results published in 1960 by two Yugoslavian
surgeons who described their use of leeches to relieve venous congestion caused by skin
implants. The work was published in the British Journal of Plastic Surgery.17 Since then,
leeches have been used in the repair of grafted skin flaps and the removal of congested
venous blood in digital, scalp and external ear reimplantations.18 Leeches have also been
studied where other treatments have failed to provide relief for the pain and inflammation
of osteoarthritis. Other uses include breast reconstruction after a mastectomy, treatment of
black eyes and reduction of postoperative swelling.
Like maggots, leeches were cleared by the 510(k) process. According to the June
2004 FDA Talk Paper, the agency announced that leeches meet the definition of a device
because they are considered to be an article intended to “diagnose, cure, treat, prevent
or mitigate a disease or condition, or to affect a function or structure of the body that
does not achieve its primary effect through a chemical action and is not metabolized.”19
According to the FDA website, leeches are indicated to help heal skin grafts by remov-
ing blood pooled under the graft and to restore blood circulation in blocked veins by
as devices by virtue of their mechanical effects of chewing and removing dead tissue. The
predicate devices included scalpels and maggots sold by Lederle Laboratories.
Sherman believes that the device classification was one of convenience, as maggots
also produce substances that kill bacteria and stimulate the growth of healthy tissue.
Proving these effects would be more difficult, however, as the documentation and meth-
odology would be extremely rigorous and time consuming. On his website, Sherman
provides a detailed description of how to make a wound dressing.9 He also published
information in two articles in 1996 and 1997.10,11 It is of interest that Sherman found that
80% of maggot-treated wounds had all dead tissue removed, compared with just 48% of
wounds that are surgically debrided. Maggot-treated patients may also spend fewer days
on an antibiotic regimen.
Leeches
Leeches are closely related to earthworms and lugworms. They thrive in mountain lakes,
desert oases and even polar oceans. There are 650 known species, and unlike other worms,
leeches have a sucker at each end, one for feeding and one for hanging on. The medicinal
leech (Hirudo medicinalis) has three jaws with 100 teeth in each. The specific value of leech
therapy is related to the properties of its bite. Leeches secrete hirudin, a direct thrombin
inhibitor.12 Other substances produced by leeches include a vasodilator, hyaluronidase,
and an anesthetic.13 Hyaluronidase is an enzyme that increases the permeability of leech
saliva through human tissue and also exhibits antibiotic properties. The leech is also
unique in that its digestive tract contains a single bacterial species, Aeromonas veronii. This
organism may inhibit the proliferation of other bacteria.
Although only cleared by FDA in 2004, the medicinal leech has been used for eons,
even earlier than maggots. Their use was first recorded in 200 BC, and according to
historians, such therapy began even earlier in India.14 In the Napoleonic era, the Empress
Josephine was treated with leeches after a fall. Napoleon’s military surgeon advocated
using 30 to 50 leeches at a time, enough to draw up to 1-1/2 quarts of blood.15 (Leeches
can consume more than five times their body weight.) At that time, it was estimated than
more than 40 million leeches were used annually in France.16 In the late 1800s, leeching
became so popular that the common preferred variety became an endangered species.
The great advantage was that leeches could extract blood with very little pain and could
be used on almost any part of the body. By the early part of the 20th century, however, the
use of leeches in medical treatment was in steep decline.
Rediscovery and Regulatory Issues
The late 20th century saw a renewed interest in leeches by both the lay and scientific
communities. This stemmed from clinical results published in 1960 by two Yugoslavian
surgeons who described their use of leeches to relieve venous congestion caused by skin
implants. The work was published in the British Journal of Plastic Surgery.17 Since then,
leeches have been used in the repair of grafted skin flaps and the removal of congested
venous blood in digital, scalp and external ear reimplantations.18 Leeches have also been
studied where other treatments have failed to provide relief for the pain and inflammation
of osteoarthritis. Other uses include breast reconstruction after a mastectomy, treatment of
black eyes and reduction of postoperative swelling.
Like maggots, leeches were cleared by the 510(k) process. According to the June
2004 FDA Talk Paper, the agency announced that leeches meet the definition of a device
because they are considered to be an article intended to “diagnose, cure, treat, prevent
or mitigate a disease or condition, or to affect a function or structure of the body that
does not achieve its primary effect through a chemical action and is not metabolized.”19
According to the FDA website, leeches are indicated to help heal skin grafts by remov-
ing blood pooled under the graft and to restore blood circulation in blocked veins by
