Clinical Evaluation of BMPs and Bone Marrow Stromal Cells in Orthopedic Surgery - Engineered Bone: Tissue Engineering Intelligence Unit - page 200

alginate, polylactic polyglycolic acid polymers or calcium phosphate ceramics. However, the
ideal scaffold remains to be found.
To the authors' knowledge, there are only two reported studies on the use of osteoprogenitor
cells for the repair of bone defects in human. Both are short case reports, respectively on one
and three patients.
In the first report, Quarto et al displayed promising results, with the use of a hBMSFs
loaded on hydroxyapatite scaffolds to treat large bone defects. 39 There were 3 mid-diaphyseal
bone losses, ranging 4-7 cm, in-patients aged 16 to 41 years old. Bone healing was achieved in
2 months, with a good integration at the interfaces with the host bone, and without any ad-
verse reaction. However, owing to the nature of the article itself, which was a short correspon-
dence, it is hard to conclude whether the technology applied here was a clinical success and did
improve the outcome of the patients compared to a standard bone autografting. No mention
was made on the previous treatments applied, neither on the length and the conditions of cell
culture. Furthermore, careful examination of provided radiographs 8 to 18 months after sur-
gery did not show any biodegradation of the scaffold compared to the postoperative x-rays.
Resorption rates of calcium phosphate ceramics vary inversely with the calcium phosphate
ratio, and hydroxyapatite is known to be almost undegradable when implanted in vivo. It is
likely that the choice of the scaffold was here non-optimal.
More recently, Vacanti et al reported the case of a 36-year old man who had a traumatic
avulsion of the distal phalanx of the thumb. 40 Reconstruction of this bone was performed
using culture-expanded osteoprogenitor cells isolated from the periosteum and seeded on a
pre-shaped coralline scaffold. At 28 months follow-up, the thumb had normal length, but
strength was reduced compared to the opposite side (25%), and no active motion was observed
at the interphalangeal joint. A biopsy of the implant performed 10 months after surgery showed
only 5% of newly formed bone within the pores.
Although non-optimal, these studies definitely show that the use of local cell therapy for the
treatment of bone defects is feasible, and these modalities will probably supersede the need of
bone grafting in the near future. However, to clearly demonstrate the benefits and the superior-
ity of these expensive technologies, they should be objectively compared to established treat-
ments in prospective randomised trials.
Conclusion
Based on their outstanding osteoinductive capacity, the BMPs offer promising perspectives
for a large number of patients suffering from long bones nonunions or spinal disorders. The
BMPs have proven to offer beneficial effects in these indications and this might obviate the
need for bone autograft harvest procedures in the near future. From our point of view, as for
any new therapeutic approach, the application of this expensive technology must be limited
until clear data on efficacy and safety are available for widespread use in clinical practice.
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