Surgical Retrieval, Isolation and <em>In vitro</em> Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

Injury to the ACL is a commonly encountered problem in active individuals. Even partial tears of this intra-articular knee ligament lead to biomechanical ...

Southern Illinois University School of Medicine

Vesicular stomatitis virus (VSV), a prototype of non-segmented negative strand RNA viruses, packages an RNA-dependent RNA polymerase (L) which, together with an associated phosphoprotein (P), transcribes the genome RNA, in vitro and in vivo, into mRNAs that are capped at the 5'-ends. However, unlike cellular guanlylyltransferase (GT), the RNA polymerase incorporates GDP in the capped structure, as Gp(alpha)p(beta)-p(alpha)A. In an effort to characterize the capping activity of the RNA polymerase, we have purified recombinant L (rL) protein expressed in insect cells. The rL, like the virion L polymerase, also caps transcribed mRNAs with identical unique cap structure. Interestingly, the purified rL is found to be tightly bound to the GT of the insect cell during all stages of purification. VSV grown in baby hamster kidney cells also packages cellular GT of the murine cell, suggesting that VSV L protein or its associated proteins may have a strong affinity for the cellular GT. The GT bound to rL, however, formed E-GMP complex, whereas no such complex was detected with the rL protein. It appears that the L protein may contain the putative active site for the unique capping reaction or the tightly bound cellular GT may by some unknown mechanism participate in the unique capping reaction.

Unique capping activity of the recombinant RNA polymerase (L) of vesicular stomatitis virus: association of cellular capping enzyme with the L protein.

Our laboratory's recent observations that transcriptionally inactive phosphoprotein (P) mutants can efficiently function in replicating vesicular stomatitis virus (VSV) defective interfering particle in a three-plasmid-based (L, P, and N) reverse genetics system in vivo (A. K. Pattnaik, L. Hwang, T. Li, N. Englund, M. Mathur, T. Das, and A. K. Banerjee, J. Virol. 71:8167-8175, 1997) led us to propose that a tripartite complex consisting of L-(N-P) protein may represent the putative replicase for synthesis of the full-length genome RNA. In this communication we demonstrate that such a complex is indeed detectable in VSV-infected BHK cells. Furthermore, coexpression of L, N, and P proteins in Sf21 insect cells by recombinant baculovirus containing the respective genes also resulted in the formation of a tripartite complex, as shown by immunoprecipitation with specific antibodies. A basic amino acid mutant of P protein, P260A, previously shown to be inactive in transcription but active in replication (T. Das, A. K. Pattnaik, A. M. Takacs, T. Li, L. N. Hwang, and A. K. Banerjee, Virology 238:103-114, 1997) was also capable of forming the mutant [L-(N-Pmut)] complex in both insect cells and BHK cells. Sf21 extract containing either the wild-type P protein or the mutant P protein along with the L and N proteins was capable of synthesizing 42S genome-sense RNA in an in vitro replication reconstitution reaction. Addition of N-Pmut or wild-type N-P complex further stimulated the synthesis of the genome-length RNA. These results indicate that the transcriptase and replicase complexes of VSV are possibly two distinct entities involved in carrying out capped mRNAs and uncapped genome and antigenome RNAs, respectively.

Identification of a novel tripartite complex involved in replication of vesicular stomatitis virus genome RNA.

Understanding the biology of cranial suture fusion and the precise role of involved molecules implicated in the process will help to identify key factors involved in regulation of suture fusion. Modulation of these key factors may serve as a tissue-engineering technique to replace the traditional surgical procedures for the correction of premature suture fusion. Modulation of gene expression by RNA interference is a widely used technique with high potential. Because there is no available report of calvarial organ transfection in vitro, the authors studied the development of a successful nonviral delivery technique of small inhibitory RNA (siRNA) to an in vitro calvarial organ culture system.

Nonviral transfection of mouse calvarial organ in vitro using Accell-modified siRNA.

Determination of gene expression is essential for understanding the role of a given gene in normal cell growth or disease processes. Recently, newly described microRNAs have been shown to play a key role in the regulation of gene expression; in particular, deregulation of microRNAs is often associated with a variety of human disorders including cancer. Although microRNAs are small RNA molecules with about 20-23 nucleotides in length and detection of their expression is believed to be challenging, with the introduction of modified nucleotides such as locked nucleic acid, the specificity and sensitivity of detection have been greatly improved. There are many methods developed for microRNA detection, but our focus in this chapter is on in situ hybridization (ISH) detection of microRNAs. We have successfully used ISH to detect several microRNAs in paraffin-embedded tumor specimens or cells-cultured in vitro.

Detection of microRNAs in cultured cells and paraffin-embedded tissue specimens by in situ hybridization.

The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic-co-glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3-E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3-E1 and hBMSCs cells exhibited normal, non-stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p < 0.05) among all composites. Gene expression of alkaline phosphatase, collagen I, osteocalcin, osteopontin, Runx-2, and Bone Sialoprotein was observed on all composites. In conclusion, SWCNT/PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications.

Single walled carbon nanotube composites for bone tissue engineering.

The purpose of this study was to develop three-dimensional single-walled carbon nanotube composites (SWCNT/PLAGA) using 10-mg single-walled carbon nanotubes (SWCNT) for bone regeneration and to determine the mechanical strength of the composites, and to evaluate the interaction of MC3T3-E1 cells via cell adhesion, growth, survival, proliferation, and gene expression. PLAGA (polylactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated, characterized, and mechanical testing was performed. MC3T3-E1 cells were seeded and cell adhesion/morphology, growth/survival, proliferation, and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, nonstressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared with PLAGA. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration, for bone tissue engineering, and are promising for orthopedic applications as they possess the combined effect of increased mechanical strength, cell proliferation, and gene expression. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2014.

Ashim Gupta

Department of Medical Microbiology,
Immunology & Cell Biology,
Department of Medical Microbiology, Immunology & Cell Biology

Southern Illinois University School of Medicine

Surgical Retrieval, Isolation and In vitro Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

Ashim Gupta

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Medical Microbiology,Immunology & Cell Biology,Department of Medical Microbiology, Immunology & Cell Biology

Southern Illinois University School of Medicine

Surgical Retrieval, Isolation and In vitro Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

Department of Medical Microbiology,
Immunology & Cell Biology,
Department of Medical Microbiology, Immunology & Cell Biology