On the mechanisms of biocompatibility.

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Articular cartilage was predicted to be one of the first tissues to successfully be regenerated, but this proved incorrect In contrast, bone (but also vasculature and cardiac tissues) has seen numerous successful reparative approaches, despite consisting of multiple cell and tissue types and, thus, possessing more complex design requirements Here, we use bone-regeneration successes to highlight cartilage-regeneration challenges: such as selecting appropriate cell sources and scaffolds, creating biomechanically suitable tissues, and integrating to native tissue We also discuss technologies that can address the hurdles of engineering a tissue possessing mechanical properties that are unmatched in human-made materials and functioning in environments unfavorable to neotissue growth

/pdf/unlike-bone-cartilage-regeneration-remains-elusive-1v15bd07dw.pdf

Unlike Bone, Cartilage Regeneration Remains Elusive

Mesenchymal stem cells (MSCs) hold great promise as therapeutic agents in regenerative medicine. Numerous animal studies have documented the multipotency of MSCs, showing their capabilities for differentiating into orthopedic tissues such as muscle, bone, cartilage, and tendon. However, the safety of culture expanded MSCs for human use has only just begun to be reported. Methods: Between 2006 and 2010, two groups of patients were treated for various orthopedic conditions with cultureexpanded, autologous, bone marrow-derived MSCs (group 1: n=50; group 2: n=290-one patient in both groups). Cells were cultured in monolayer culture flasks using an autologous platelet lysate technique and re-injected into peripheral joints or into intervertebral discs with use of c-arm fluoroscopy. While both groups had prospective surveillance for complications, Group 1 additionally underwent 3.0T MRI tracking of the re-implant sites. Results: The mean age of patients treated was 53 +/- 13.85 years; 214 were males and 125 females with mean follow-up time from any procedure being 435 days +/- 261 days. Number of contacts initiated based on time from first procedure was 482 at 3 months, 433 at 6 months, 316 contacts at 12 months, 110 contacts at 24 months, and 22 contacts at 36 months. For Group 1, 50 patients underwent 210 MRI surveillance procedures at 3 months, 6 months, 1, 2, and 3 years which failed to demonstrate any tumor formation at the re-implant sites. Formal disease surveillance for adverse events based on HHS criteria documented significantly less morbidity than is commonly reported for more invasive surgical procedures, all of which were either self-limited or were remedied with therapeutic measures. Two patients were diagnosed with cancer out of 339 patients treated since study inception; however, this was almost certainly unrelated to the MSC therapy and the neoplasm rate in similar to that seen in the U.S. Caucasian population. Knee outcome data was collected on a subset of patients. Here, > 75% improvement was reported in 41.4% while decreasing the improvement threshold to > 50% improvement, 63.2% reported an improvement. At an average reporting time of 11.3 months from first procedure average reported relief in the knee sample equaled 53.1% (n=133 reporting). Conclusions: Using both intensive high field MRI tracking and complications surveillance in 339 patients, no neoplastic complications were detected at any stem cell re-implantation site. These findings are consistent with our prior publication and other published reports that also show no evidence of malignant transformation in vivo, following implantation of MSCs for orthopedic use.

/pdf/safety-and-complications-reporting-update-on-the-re-3vv7ffadke.pdf

Safety and Complications Reporting Update on the Re-Implantation of Culture-Expanded Mesenchymal Stem Cells Using Autologous Platelet Lysate Technique

Ever since synovium-derived mesenchymal stem cells (SMSCs) were first identified and successfully isolated in 2001, as a brand new member in MSC families, they have been increasingly regarded as a promising therapeutic cell species for musculoskeletal regeneration, particularly for reconstructions of cartilage, bones, tendons, and muscles. Besides the general multipotency in common among the MSC community, SMSCs excel other sourced MSCs in higher ability of proliferation and superiority in chondrogenesis. This review summarizes the latest advances in SMSC-related studies covering their specific isolation methodologies, biological insights, and practical applications in musculoskeletal therapeutics of which an emphasis is cast on engineered chondrogenesis.

Synovium-derived mesenchymal stem cells: a new cell source for musculoskeletal regeneration.

Cartilage repair using an in vitro generated scaffold-free tissue-engineered construct derived from porcine synovial mesenchymal stem cells

The purpose of this study was to characterize a tissue-engineered construct (TEC) generated with human synovial mesenchymal stem cells (MSCs). MSCs were cultured in medium with ascorbic acid 2-phosphate (Asc-2P) and were subsequently detached from the substratum. The detached cell/matrix complex spontaneously contracted to develop a basic TEC. The volume of the TEC assessed by varying initial cell density showed that it was proportional to initial cell densities up to 4 x 10(5) cells/cm(2). Assessment of the mechanical properties of TEC using a custom device showed that the load at failure and stiffness of the constructs significantly increased with time of culture in the presence of Asc-2P, while in the absence of Asc-2P, the constructs were mechanically weak. Thus, the basic TEC possesses sufficiently self-supporting mechanical properties in spite of not containing artificial scaffolding. TEC further cultured in chondrogenic media exhibited positive alcian blue staining with elevated expression of chondrogenic marker genes. Based on these findings, such human TEC may be a promising method to promote cartilage repair for future clinical application.

In vitro generation of a scaffold-free tissue-engineered construct (TEC) derived from human synovial mesenchymal stem cells: biological and mechanical properties and further chondrogenic potential.

Daisuke Katakai

Papers

Cartilage repair using an in vitro generated scaffold-free tissue-engineered construct derived from porcine synovial mesenchymal stem cells

In vitro generation of a scaffold-free tissue-engineered construct (TEC) derived from human synovial mesenchymal stem cells: biological and mechanical properties and further chondrogenic potential.

Compressive properties of cartilage-like tissues repaired in vivo with scaffold-free, tissue engineered constructs.

Mechanical properties of synovial cell-seeded 3-D constructs for cartilage regeneration: Effects of cyclic compressive stress

Tensile properties of a scaffold-free 3-D synthetic tissue cultured from synovium-derived cells