Abstract
We hypothesized that the transplantation of Scx-transduced tendon-derived stem cells (TDSCs) promoted better tendon repair compared to the transplantation of mock-transduced cells. This study thus aimed to investigate the effect of Scx transduction on the expression of lineage markers in TDSCs and the effect of the resulting cell line in the promotion of tendon repair. Rat non-GFP or GFP-TDSCs were transduced with Scx or empty lentiviral vector (Mock) and selected by blasticidin. The mRNA expressions of Scx and different lineage markers were examined by qRT-PCR. The effect of the transplantation of GFP-TDSC-Scx on tendon repair was then tested in a rat unilateral patellar tendon window injury model. The transplantation of GFP-TDSC-Mock and scaffold-only served as controls. At week 2, 4 and 8 post-transplantation, the repaired patellar tendon was harvested for ex vivo fluorescent imaging, vivaCT imaging, histology, immunohistochemistry and biomechanical test. GFP-TDSC-Scx consistently showed higher expressions of most of tendon- and cartilage- related markers compared to the GFP-TDSC-Mock. However, the effect of Scx transduction on the expressions of bone-related markers was inconclusive. The transplanted GFP-TDSCs could be detected in the window wound at week 2 but not at week 4. Ectopic mineralization was detected in some samples at week 8 but there was no difference among different groups. The GFP-TDSC-Scx group only statistically significantly improved tendon repair histologically and biomechanically compared to the Scaffold-only group and the GFP-TDSC-Mock group at the early stage of tendon repair. There was significant higher expression of collagen type I in the window wound in the GFP-TDSC-Scx group compared to the other two groups at week 2. The transplantation of GFP-TDSC-Scx promoted healing at the early stage of tendon repair in a rat patellar tendon window injury model.
Highlights
Scleraxis (Scx) is a basic helix-loop helix transcription factor which is present in tendon starting from the condensation stage and persists into adulthood [1]
The lentiviral particles collected were used for the infection of tendon-derived stem cells (TDSCs) isolated from one non-Green Fluorescent Protein (GFP) SD rat and 2 GFP SD rats at passage 1–2 (P1–2)
We reported that the transplantation of GFP-TDSC-Scx histologically and biomechanically promoted better tendon repair compared to the GFPTDSC-Mock and Scaffold-only groups at the early stage after injury
Summary
Scleraxis (Scx) is a basic helix-loop helix (bHLH) transcription factor which is present in tendon starting from the condensation stage and persists into adulthood [1]. Scx forms heterodimer with NFAT-C (Nuclear factor of activated T-cells, cytoplasmic) and directly regulates gene transcription of collagen type I (Col1a1), which encodes the most abundant extracellular matrix protein in tendons [2]. Scx is a key regulator of tendon differentiation [3]. The extracellular matrix composition of the repaired tendon is changed, with ectopic chondro-ossification in some tendon samples at the later stage of repair [4]. Erroneous cell differentiation to the non-tenocyte lineages during tendon repair might account for ectopic chondro-ossification in tendons after injury [5,6]. The biomechanical properties were compromised [7], which might account for the high re-tear rate of repaired tendon
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