6
referred to as chondral or cartilage
transplantation. Other surgical proce-
dures, such as microfracture, drilling
and abrasion, may provide sympto-
matic relief, but when they do, the
benefit usually lasts only a few years,
especially if the person's pre-injury
activity level is maintained. These
procedures are performed with the
intent of allowing bone marrow cells
to infiltrate the defect, resulting in the
formation of a fibrous cartilage tissue,
which is less durable and resilient
than normal articular cartilage.
The use of allograft implants for
treating damage to the knee is a rela-
tively new and growing area. The U.
S. market for procedure-specific sur-
geries in the sports medicine sector
that used an implant grew at a 6%
average annual rate between 1997 and
1999. During 1999, there were ap-
proximately 870,000 procedure-
specific surgeries in the U.S. that used
an implant. Of these 870,000 proce-
dures, approximately 52,000 involved
the use of an allograft implant, ac-
counting for approximately $73.0
million in revenues. During this type
of procedure, the surgeon transplants
the allografts into a patient's body to
make the needed repair, similar in the-
ory to organ transplantation.
A major supplier of allografts for
implantation is
Regeneration Tech-
nologies. Regeneration Technologies
processes allograft tissue, which is
tissue recovered from deceased human
donors, for biologic safety and im-
plants mechanical characteristics. The
company's goal is to replace conven-
tional implant approaches, including
metals, synthetics and autograft im-
plants with allograft, and to establish
its allografts as the implant of choice
for tissue repair. Regeneration Tech-
nologies currently has several sports
medicine allografts in development,
including soft-tissue tacks used for
reconstruction of soft-tissue tears,
such as rotator cuff injuries, and non-
frozen osteochondral allografts used
for repair of articulating surfaces and
joints. Regeneration Technologies
believes their human tissue implants,
which focus on the highest-volume
procedures in the sports medicine
market, primarily shoulder and knee
procedures, can improve surgical out-
comes.
Transplantation of allografts is
the method of choice for certain medi-
cal conditions, such as organ failure,
where whole healthy organs are trans-
planted from a donor to a recipient.
However,
BSR is not convinced that
cartilage transplants are a good
choice, especially if alternative proce-
dures utilizing autografts are avail-
able. Additionally, cartilage allografts
are associated with similar risks that
accompany organ transplants, such as
potential for passing on infectious
agents and rejection of the allograft.
In fact, rejection of cartilage allografts
has been reported in the scientific lit-
erature and will continue to plague
Regeneration Technologies. To its
credit, the company is implementing
procedures to cleanse the tissues of
infectious agents that reside outside
cells and to minimize immunogenic-
ity. Unfortunately, complete elimina-
tion of infectious agents and immuno-
genic molecules will decrease the vi-
ability of the graft.
With recent advances in biotech-
nology, damaged knee cartilage can
be repaired using the patient's own
cells, or autografts. For knee cartilage
damage, chondrocytes (cells that
make up cartilage) can be propagated
in cell culture from a small sample, or
biopsy, of cartilage from the injured
knee, collected via arthroscopic sur-
gery. Once millions of new chondro-
cytes are grown in cell culture, they
are sent to the surgeon for implanta-
tion into the damaged area of the
knee. Two biotechs are involved in
this technology, Genzyme Biosurgery
and Advanced Tissue Sciences. The
leader in this area is Genzyme Biosur-
gery, as it is currently marketing Car-
ticel as a treatment option since 1995.
Carticel is composed of autologous
cultured chondrocytes derived from
the patient and grown in the labora-
tory for implantation. Advanced Tis-
sue Sciences is in early phase devel-
BioTech Sage Report, January 2001
