ObjectiveThe objective of this study was to evaluate the efficacy of quantitative T2 magnetic resonance imaging (MRI) for quantifying early cervical intervertebral disc (IVD) degeneration in asymptomatic young adults by correlating the T2 value with Pfirrmann grade, sex, and anatomic level.MethodsSeventy asymptomatic young subjects (34 men and 36 women; mean age, 22.80±2.11 yr; range, 18–25 years) underwent 3.0-T MRI to obtain morphological data (one T1-fast spin echo (FSE) and three-plane T2-FSE, used to assign a Pfirrmann grade (I–V)) and for T2 mapping (multi-echo spin echo). T2 values in the nucleus pulposus (NP, n = 350) and anulus fibrosus (AF, n = 700) were obtained. Differences in T2 values between sexes and anatomic level were evaluated, and linear correlation analysis of T2 values versus degenerative grade was conducted.FindingsCervical IVDs of healthy young adults were commonly determined to be at Pfirrmann grades I and II. T2 values of NPs were significantly higher than those of AF at all anatomic levels (P<0.000). The NP, anterior AF and posterior AF values did not differ significantly between genders at the same anatomic level (P>0.05). T2 values decreased linearly with degenerative grade. Linear correlation analysis revealed a strong negative association between the Pfirrmann grade and the T2 values of the NP (P = 0.000) but not the T2 values of the AF (P = 0.854). However, non-degenerated discs (Pfirrmann grades I and II) showed a wide range of T2 relaxation time. T2 values according to disc degeneration level classification were as follows: grade I (>62.03 ms), grade II (54.60–62.03 ms), grade III (<54.60 ms).ConclusionsT2 quantitation provides a more sensitive and robust approach for detecting and characterizing the early stage of cervical IVD degeneration and to create a reliable quantitative in healthy young adults.

The aims of this study were to construct the composite of poly (L-lactic-co-glycolic acid) (PLGA) scaffold-nucleus pulposus (NP) cells using tissue engineering methods and to investigate the in vivo performance of the composite in a canine model. NP cells were isolated from the lumbar intervertebral discs of a beagle dog. NP cells were cultured, expanded in vitro, and seeded onto a three-dimensional porous PLGA scaffold. The composite was tested in 18 beagle dogs that were randomly divided into three groups: nucleotomy alone (A), nucleotomy with PLGA implantation (B), and nucleotomy with PLGA scaffold/NP cells composite implantation (C). X-ray and magnetic resonance imaging were performed pre- and postoperatively. Evaluation of disc height, segment stability, and biomechanics and immunohistochemical analysis were performed. Dog NP cells attached and showed proliferation activity within the PLGA scaffold in vitro and in vivo. Disc height, segmental stability, and T2-weighted signal intensity on magnetic resonance imaging scans were well preserved in group C dogs with the engineered composite. PHK-26-positive cells were found within the area of the NP 8 weeks postoperatively. The NP cell-PLGA scaffold composite can prevent or delay the degeneration process after nucleotomy in the canine model. This hybrid composite might be a promising construct for intervertebral disc regeneration.

Nucleus pulposus (NP) tissue engineering has been proposed as a novel biological treatment for early-stage intervertebral disc degeneration. In this study, a novel functional self-assembling peptide PKP was first designed by linking the short functional motif of bone morphogenetic protein-7 (BMP7) to the C-terminal of RADA16-I, and another new functional self-assembling peptide was obtained by mixing RKP with RADA16-I. Then, the biocompatibilities and bioactivities of RKP and RAD-RKP for human degenerated nucleus pulposus cells (hNPCs) were studied in vitro. Atomic force microscopy and scanning electron microscopy (SEM) confirmed that both RKP and RAD-RKP could self-assemble into three-dimensional (3D) nanofiber hydrogel scaffolds in a culture medium at 37°C. After the hNPCs were cultured in 3D scaffolds, both RKP and RAD-RKP exhibited reliable attachment and extremely low cytotoxicities (<14%), which were verified by SEM and cytotoxity assays, respectively. Our results also showed that the functional-based scaffolds could increase the proliferation and migration of hNPCs after 7 days compared with culture plates and pure RADA16-I. Quantitative real-time polymerase chain reaction demonstrated that the expressions of collagen II α1, Sox-9, and aggrecan were upregulated, while collagen I α1 was downregulated by functional-based scaffolds after 28 days. Furthermore, we also confirmed that RAD-RKP exhibited a higher hNPC proliferation, migration, and expression of Sox-9 and aggrecan compared with pure RKP. Therefore, the results of this study indicated that the BMP7 short motif-designed functional self-assembling peptide nanofiber hydrogels could be used as excellent scaffolds in NP tissue engineering, and RAD-RKP might have further potential application in human mild degenerated NP tissue regeneration.

Bone morphogenetic protein-7 (BMP-7) was found to stimulate the synthesis of proteoglycans (PGs) and collagen type II. To increase the biological function of the nucleus pulposus (NP) cells, the Ad-hBMP-7 vector was also successfully constructed and transfected NP cells. However, the disadvantages of adenovirus limit the usefulness of the Ad-hBMP7 vector for clinical application. The rAAV2 vector has empirical advantages, especially for clinical use, to transfer exogenous genes into cells. The purpose of this study was to first determine whether a rAAV2-hBMP-7 vector could be used to transfect canine NP cells and effect on the biological functions of canine NP cells. The canine NP cells transfected by the rAAV-BMP7 were assessed semi-quaiitatively for BMP-7 expression with real-time PCR and westernbloting. Aggrecan and collagens type I and II secreted by the NP cells were qualitatively assessed at 4, 7, and 14 days post-transfection in the transfection and control groups. We found that rAAV2 can successfully transfer the hBMP-7 gene into canine NP cells. NP cells transfected by the rAAV-hBMP-7 vector express hBMP-7 for at least 14 days. At 7 and 14 days, the expressed hBMP-7 promotes a remarkable and significant accumulation of both proteoglycans (42% and 77% higher than non-transfected cells) (p<0.05) and collagen type II (63% and 94% higher than non-transfected cells) (p<0.05). Thus, we could speculate that the rAAV-based gene delivery technique promotes the expression of proteoglycans and collagen type II of nucleus pulposus cells. Moreover, this technique may be applicable for the future treatment of degenerative disc disease. ß

The aim of this study was to evaluate whether human Wharton's jelly cells (WJCs) could be differentiated into nucleus pulposus (NP)-like cells by coculturing with NP cells (NPCs) in vitro. WJCs were isolated from the human umbilical cord, and NPCs were isolated from healthy human intervertebral disc. After coculturing WJCs with NPCs in a monolayer environment with or without cell-cell contact for 7 days, the real-time polymerase chain reaction showed the relative gene expressions of NP-marker genes (aggrecan, type II collagens, and SRY-type HMG box-9) were significantly increased (p<0.05) in all groups, and the increase in the group of 25:75/WJCs:NPCs was the largest (p<0.05). The increases of relative gene expression in WJCs cocultured with cell-cell contact were larger than those cocultured without contact in all ratios (p<0.05). WJCs were positive for telomerase expression. Flow cytometry analyses showed that WJCs expressed CD73, CD105, CD90, CD29, CD166, and human leukocyte antigen (HLA)-ABC while being negative for the expression of CD34, CD45, and HLA-DR. The results of this study indicated that the WJCs had the feature of the mesenchymal stem cell and might be induced to differentiate to NP-like cells by coculturing with NPCs.