Temporal and Spatial Expression of TGF-b1 in the Early Phase of Patellar Tendon Healing after Application of Platelet Rich Plasma.

BACKGROUND: The aim of this study is to find out the spatial and temporal expression of TGF-b1 during the tendon healing, after application of Platelet Rich Plasma (PRP). METHODS: A patellar tendon defect model in rabbits was used for this purpose. 48 skeletally mature New Zealand White rabbits, weighing 3.5 kg, were used for this study. Equal numbers of animals from both groups were sacrificed at 4 different time points (1st, 2nd, 3rd, and 4th week). A full thickness patellar tendon substance in the right limb of each animal was excised from its central portion during the operation. PRP with a gel form was applied and filled the tendon defect in PRP group. No PRP was applied in the tendon defect of controls. Histological sections with hematoxylin-eosin and immunohistochemical sections with an anti-TGF-b1 primary antibody were made for the evaluation of the results. RESULTS: A differentiation of the healing process was observed in the PRP group in comparison with the control group. TGF-b1 expression was detected in various cell populations (inflammatory cells, endothelial cells, macrophages, and tenocytes). Both cytoplasmic and nuclear expressions were present. The larger amounts of immunoexpression were localized in epitenon and in the repair site. PRP group showed stronger and more extensive staining at 1st and 2nd week (P<0.0001), whereas control group showed more extensive staining at the 3(rd) and 4(th) week (P<0.0001). CONCLUSIONS: Our study demonstrates that locally application of PRP result in an alteration of TGF-b1 expression during the healing of a patellar tendon defect.

Does a single application of PRP alter the expression of IGF-I in the early phase of tendon healing?

The purpose of this study was to determine whether or not a single application of platelet-rich plasma (PRP) in a ruptured tendon alters the expression of IGF-I in the early phase of healing in an animal wound model. We performed an Achilles tendon rupture model on 48 New Zealand white rabbits, by transecting the tendon transversely and then injecting 0.5 mL of PRP into the tendon mass on one side, and injecting saline on the contralateral, control side. Twenty-four animals received PRP (PRP group), and 24 animals served as untreated controls (control group). Six animals (12 limbs) were killed from each group at 1, 2, 3, and 4 weeks postoperatively. After the animals were killed, 6 paraffin sections were made from each Achilles tendon, 3 of which were stained with hematoxylin and eosin and subjected to microscopic examination, and 3 of which were immunostained with an anti-IGF-I primary antibody. Density of brown diaminobenzidine (DAB) staining was evaluated to quantitatively analyze the results. IGF-I was expressed intracellularly in various cell types throughout the entire healing phase. The growth factor was localized in the epitenon and the endotenon, with an overexpression in the epitenon in the PRP group by the fourth week in comparison with the controls. Furthermore, the tendons treated with PRP healed more rapidly. Based on these findings, PRP could be useful to surgeons treating ruptured tendon.

Immunohistochemical study of angiogenesis after local administration of platelet-rich plasma in a patellar tendon defect.

A full thickness defect was made in the central portion of the patellar tendon of 48 New Zealand white rabbits. Platelet-rich plasma (PRP) gel was then applied and filled the tendon defect. The same procedure was performed in the control group, without the application of PRP. Animals were sacrificed after one, two, three, and four weeks. Histological and immunohistochemical analyses using a monoclonal antibody against CD31 were performed. The histological examination showed a superior healing process in the PRP group compared with the control group. Especially in the third week, the tissue formed in the PRP group was more mature and dense with less elastic fibres remaining. Neovascularisation was significantly higher in the PRP group during the first two weeks and significantly lower in the third and fourth weeks (p < 0.0001). Histological examination and study of angiogenesis showed that the application of PRP enhances and accelerates the tendon healing process.

The effect of platelet-rich plasma gel in the early phase of patellar tendon healing.

INTRODUCTION: The aim of this study is to assess if an application of platelet-rich plasma (PRP) gel would improve the mechanical properties of rabbit's patellar tendon after resecting its central portion. MATERIALS AND METHODS: Forty skeletally mature New Zealand White rabbits were used. Two groups ten rabbits each (PRP and control group) were used to evaluate mechanical properties and histology after 14 days and two groups ten rabbits each (PRP and control groups) were used to evaluate mechanical properties and histology after 28 days. RESULTS: At 14 days, PRP group showed a 72.2% increase in force at failure, a 39.1% increase in ultimate stress, and a 53.1% increase in stiffness, as compared with controls. These changes were statistically significant (P < 0.05). At 28 days, there was no longer any significant difference between PRP and control groups (P > 0.05). DISCUSSION: In our study, the mechanical properties of the regenerated tendon in the PRP group were significantly improved in relation to the control group. It appears that PRP has a strong effect in the early phase of tendon healing. This effect is probably due to the growth factors that are released from the platelets during activation.

Progression of spondylolysis to isthmic spondylolisthesis in an adult without accompanying disc degeneration: a case report.

Progression of spondylolysis to spondylolisthesis in adults is very rare. It is always accompanied by disc degeneration at the slip level, or at a lower level. The intervertebral disc is indeed the main structure that opposes the anteriorly directed shear forces. Of course, the disc degeneration might also be a consequence, rather than a cause of the slip. The authors describe an unusual case of progression of spondylolysis to spondylolisthesis in an adult, without any disc degeneration. They are not aware of a similar case in the literature. In 1999, an aircraft engineer with known asymptomatic spondylolysis was involved in a low impact motorcycle accident, after which a Grade I spondylolisthesis L4 was diagnosed. There was no predisposing disc space narrowing at any vertebral level. There may have been a certain degree of microscopic disc degeneration L4L5, a possibility which was confirmed by the development of a disc hernia L4L5, seven years after trauma. This case illustrates the potential for progression of spondylolysis to spondylolisthesis in an adult, without radiographical signs of disc degeneration at any level. The minimal trauma might have played a role. The authors recommend that patients with known spondylolysis who sustain acute exacerbation of their back pain should have standing radiographs.

Comparative study of 5 different membranes for guided bone regeneration of rabbit mandibular defects beyond critical size.

BACKGROUND: Although several studies have examined use of collagen membranes in guided bone regeneration (GBR), none has examined the use of human fascia temporalis as a bioabsorbable barrier. The majority of studies related to GBR have examined critical size defects. We sought to assess the human fascia temporalis and other well-documented membranes applied for GBR in mandibular osseous defects beyond critical size. MATERIAL/METHODS: Fifty adult male New Zealand white rabbits were used in this study. Five groups of 10 animals each were used: HFL (human fascia lata membrane), HP (human pericardium), HFT (human fascia temporalis), BP (bovine pericardium), and PTFE (expanded polytetrafluoroethylene). Animals were killed 10 weeks after membrane application. In each animal, 9-mm circular mandibular defects were created bilaterally. On 1 side of the jaw, the defect was covered with 1 of the test membranes; the defect on the other side served as a control. Harvested specimens were examined histologically. RESULTS: Membranes were significantly superior to the controls in all animals (P<0.001). Paired comparisons showed that groups HFL, HP, BP, and PTFE were significantly superior to HFT (P<0.05). Conversely, comparisons of HFL-HP, HFL-BP, HFL-PTFE, HP-BP, HP-PTFE, and BP-PTFE, showed no significant differences (P>0.05). CONCLUSIONS: According to our results, the fascia temporalis is not recommended for GBR techniques. The fascia lata, human pericardium, bovine pericardium, and e-PTFE advance bone regeneration and can be successfully used as GBR membranes for osseous defects beyond the critical size.