Biofabrication is a popular technique to produce personalized constructs for tissue engineering. In this study we combined laponite (Lap), gellan gum (GG) with platelet-rich plasma (PRP) aiming to enhance the endothelial regeneration through the synergistic effects of their individual properties. Laponite has the ability to form porous three-dimensional networks mimicking the extracellular matrix structure, and PRP delivery of growth factors stimulates the endothelial cell proliferation and migration, offering a composite bioink for cell growth and support. The sustained release of these growth factors from the GG-laponite-PRP composite material over time provides a continuous source of stimulation for the cells, leading to more effective tissue engineering strategies for endothelial tissue regeneration. Four blend compositions comprising 1% w/v GG and 0.5 or 1% w/v Lap and 25% v/v PRP were combined with Wharton jelly mesenchymal stem cells (WJ-MSCs) and bioprinted into vessel-like structures with an inner diameter of 3 mm and a wall thickness of 1 mm. Stress/strain analysis revealed the elastomeric properties of the hydrogels with Young modulus values of 10 MPa. Increasing the Lap concentration led to a non-significant decrease of swelling ratio from 93 to 91%. Live/dead assay revealed cell viability of at least 76%, with the 0.5%Lap-GG viability exceeding 99% on day 21. Gradual increase of glycosaminoglycans accumulation and collagen production indicate promotion of ECM formation. The expression and membranous localization of PECAM-1 from day 7 and the granular intracellular localization of vWF after 2 weeks demonstrate in vitro endothelial functionality. In vivo subcutaneous implantation indicated the absence of any adverse immunological reactions. The results reveal the expression of both vWF and PECAM-1 by WJ-MSCs entrapped in all four construct compositions with significantly higher expression of vWF in the presence of PRP.

It has been proposed that intervertebral disc degeneration might be caused by low-grade infection. The purpose of the present study was to assess the incidence of herpes viruses in intervertebral disc specimens from patients with lumbar disc herniation. A polymerase chain reaction based assay was applied to screen for the DNA of eight different herpes viruses in 16 patients and two controls. DNA of at least one herpes virus was detected in 13 specimens (81.25%). Herpes Simplex Virus type-1 (HSV-1) was the most frequently detected virus (56.25%), followed by Cytomegalovirus (CMV) (37.5%). In two patients, co-infection by both HSV-1 and CMV was detected. All samples, including the control specimens, were negative for Herpes Simplex Virus type-2, Varicella Zoster Virus, Epstein Barr Virus, Human Herpes Viruses 6, 7 and 8. The absence of an acute infection was confirmed both at the serological and mRNA level.

To our knowledge this is the first unequivocal evidence of the presence of herpes virus DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease.

The evaluation of early results of combined percutaneous pedicle screw fixation and kyphoplasty for the management of thoraco-lumbar burst fractures

Between October 2008 and April 2009, 9 patients with thoracolumbar burst fractures underwent percutaneous short-segment pedicle screw fixation and augmentation kyphoplasty with calcium phosphate cement. All patients were selected according to the type of fracture (unstable type A3 fractures based on the Magerl classification) the absence of neurological signs and an intact posterior longitudinal ligament on the pre-operative MRI scan. Patient demographics, co-morbidities and complications were recorded. The main endpoints included Cobb angle correction, vertebral body height restoration and the length of hospital stay.

There were 3 male and 6 female patients with an average age of 43.6 years. The average follow-up was 2.4 months. The mean kyphotic angulation improved from 18.40 pre-operatively to 6, 80 post-operatively. The loss of vertebral body height improved from a mean of 38.7 % pre-operatively to 12.1 % post-operatively. The average duration of surgery was 40 minutes with insignificant blood loss. There were no post-operative complications. The average length of hospital stay was 3.2 days.

The combination of percutaneous short-segment pedicle screw fixation supplemented by balloon kypho-plasty for the management of thoracolumbar burst fractures with no neurological deficit offers correction of the normal thoracolumbar anatomy as well as augmentation of the anterior load-bearing column, using a minimally invasive technique. The early results are promising