416 Canine Sports Medicine and Rehabilitation
Ligament and tendon injuries
Despite the advances in nonsurgical and surgi‑
cal techniques, treatment of tendinopathies,
desmitis, and chronic tears remain a challenge
in people and animals. Reasons for the high
failure rate include the limited potential for
healing (in chronic injuries) and the develop‑
ment of scar tissue with lower mechanical
properties than the original tissue. Stem cells
have been evaluated for treatment of tendinopa‑
thies for their potential for restarting the healing
process by differentiating into tenocytes and
releasing growth factors and cytokines. BM‐
MSCs have been evaluated in horses with super‑
ficial flexor tendon injuries, demonstrating a
significant decrease in re‐injury after return to
competition (Godwin et al., 2012).
A recent study in dogs investigated the use of
autologous bone marrow aspirate concentrate
or AD‐MSCs with PRP combination and a reha‑
bilitation therapy protocol for the treatment of
partial CCL rupture (Canapp et al., 2016b). Dogs
presenting with an early partial CCL rupture
(n = 36) were diagnosed and treated with a sin‑
gle intra‐articular injection of either bone mar‑
row aspirate concentrate or AD‐MSCs with PRP.
Outcome measures included client‐based ques‑
tionnaire (n = 12), veterinary evaluation, and
objective gait analysis (n = 11). Of the 12 ques‑
tionnaires that were returned, seven of the eight
performance dogs had returned to full activity.
The same authors described the outcomes for 55
dogs with supraspinatus tendinopathy treated
with adipose‐derived progenitor cells and PRP
therapy (Canapp et al., 2016a). After ultrasound‐
guided injection, 25 of 55 dogs were rechecked
with objective gait analysis. At 90 days follow‑
ing injection, 88% of cases had no significant dif‑
ference in total pressure index percentage
between the treated and the contralateral limb.
All cases showed improvement in fiber pattern
at ultrasonographic recheck.
Additional data are needed before making any
conclusion on the effect of MSCs in the treat‑
ment of tendinopathies in dogs. Interestingly,
in human patients, despite some promising
clinical reports, no sufficient evidence is found
to support MSC treatment for tendinopathies
(Pas et al., 2017) at this point. Additional veteri‑
nary studies are needed, with the inclusion of
standardized protocols, control groups, and
randomized design.
Intervertebral disc diseaseCurrently available treatments for intervertebral
disc disease (IVDD) in dogs focus on alleviation
of pain and include anti‐inflammatory/analgesic
medication, physiotherapy, and various surgical
procedures. All those treatment modalities may
resolve neurological deficits and reduce pain but
they do not lead to repair of the degenerated disc.
In fact, long‐term medication may be necessary
with resultant side effects, and surgical treat‑
ments can result in various complications includ‑
ing implant failure, adjacent segment disease,
and recurrence of IVDD. The problems described
above and the inability to solve them with cur‑
rent conservative and surgical approaches, have
led to a growing consensus of the need to develop
new therapies based on the methods of regen‑
erative medicine and tissue engineering.
Because there are relatively few cells in the
degenerated disc and cell viability is impaired,
stimulation of the remaining cells to proliferate
and to produce matrix is challenging. Cell‐
based therapies may overcome this problem.
Thus far, cell‐based treatment strategies have
used chondrocyte‐like cells (CLCs), MSCs, and
notochordal cells.
Autologous transplantation of CLCs has been
used successfully in an experimental canine
model (Ganey et al., 2009). After expansion of
disc chondrocytes in culture and return into the
disc by injection, transplanted cells remained
viable and produced extracellular matrix. While
clinical results in dogs are not available, this
procedure has been used in human patients.
People receiving autologous CLC transplanta‑
tion experienced a greater reduction in pain
after 2 years and had a higher intervertebral disc
(IVD) fluid content on MRI than the control
group (Hohaus et al., 2008). CLC transplantation
has its limitations because, practically, these
cells can only be obtained from herniated discs
in low numbers and with a reduction of their
chondrogenic potential as they have already
undergone degenerative alterations.
Currently, the use of MSCs is emerging as a lead‑
ing cellular treatment for several diseases, since
they can be isolated from several tissues including
bone marrow, adipose tissue, muscle, placenta,
and umbilical cord blood. Depending on their
environment, MSCs can differentiate into various
cell types, such as osteoblasts, myocytes, neural
cells, adipocytes, and chondrocytes. Besides their