IJCEM Copyright © 2008-All rights reserved. Published by e-Century Publishing Corporation, Madison, WI 53711
Int J Clin Exp Med 2010;4(3):214-219

Original Article
Tendon repair augmented with a novel circulating stem cell population

Robert J. Daher, Nadeen O. Chahine, Pasquale Razzano, Sohum A. Patwa, Nicholas J. Sgaglione, Daniel A. Grande

Department of Orthopedic Surgery at the North Shore-Long Island Jewish Health System; Department of Neurosurgery at the Feinstein
Institute for Medical Research; Department of Orthopedic Surgery at the Feinstein Institute for Medical Research; Department of
Orthopedic Surgery at the Feinstein Institute for Medical Research; Department of Orthopedic Surgery at the Feinstein Institute for
Medical Research; Department of Orthopedic Surgery at the Feinstein Institute for Medical Research, Manhasset, NY, USA.

Received July 16, 2011; accepted September 3, 2011; Epub September 15, 2011; published September 30, 2011

Abstract: Tendon ruptures are common sports-related injuries that are often treated surgically by the use of sutures followed by
immobilization. However, tendon repair by standard technique is associated with long healing time and often suboptimal repair.
Methods to enhance tendon repair time as well as the quality of repair are currently unmet clinical needs. Our hypothesis is that the
introduction of a unique stem cell population at the site of tendon transection would result in an improved rate and quality of repair.
Achilles tendons of fifty-one Sprague-Dawley rats were transected and suture-repaired.  In half of the rats, a biodegradable scaffold
seeded with allogenic circulating stem cells was placed as an onlay to the defect site in addition to the suture repair. The other half was
treated with suture alone to serve as the control group. Animals were randomized to a two-, four-, or six-week time group. At the time of
necropsy, tendons were harvested and prepared for either biomechanical or histological analysis. Histological slides were evaluated in
a blinded fashion with the use of a grading scale. By two weeks, the experimental group demonstrated a significant improvement in
repair compared to controls with no failures. Average histological scores of 0.6 and 2.6 were observed for the experimental and control
group respectively. The experimental group demonstrated complete bridging of the transection site with parallel collagen fiber
arrangement. By four weeks, both groups showed a continuing trend of healing, with the scaffold group exceeding the histological
quality of the tissue repaired with suture alone. Biomechanically, the experimental group had a decreasing cross-sectional area with
time which was also associated with a significant increase in the ultimate tensile strength of the tendons, reaching 4.2MPa by six
weeks. The experimental group also achieved a significantly higher elastic toughness by six weeks and saw an increase in the tensile
modulus, reaching 31Mpa by six weeks. The use of circulating stem cells as an adjunct in tendon repair demonstrates superior
biomechanical properties and an improved level of histological organization, when compared to the suture alone control group. These
improvements were not previously observed when gene therapy, protein therapy, or current tissue engineering technologies were
used. (IJCEM1107004).

Key words: Orthopedic surgery, sports medicine, achilles tendon, tendon repair, circulating stem cells, tendon biomechanics

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Address all correspondence to:
Daniel A. Grande, PhD
350 Community Drive
Manhasset, NY 11030
Tel: (516) 562-1138
Fax: (516) 562-1022
E-mail: dgrande@nshs.edu