Prospective Cohort Study

Tissue engineering can be used to restore, maintain, or enhance tissues and organs. The potential impact of this field, however, is far broader-in the future, engineered tissues could reduce the need for organ replacement, and could greatly accelerate the development of new drugs that may cure patients, eliminating the need for organ transplants altogether.

https://science.sciencemag.org/content/sci/295/5557/1009.full.pdf

Tissue Engineering--Current Challenges and Expanding Opportunities

https://www.oarsijournal.com/article/S1063-4584(02)90801-0/pdf

Articular cartilage repair: basic science and clinical progress. A review of the current status and prospects.

Application of chitosan-based polysaccharide biomaterials in cartilage tissue engineering : a review

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

Background Full-thickness defects of articular cartilage in the knee have a poor capacity for repair. They may progress to osteoarthritis and require total knee replacement. We performed autologous chondrocyte transplantation in 23 people with deep cartilage defects in the knee. Methods The patients ranged in age from 14 to 48 years and had full-thickness cartilage defects that ranged in size from 1.6 to 6.5 cm2. Healthy chondrocytes obtained from an uninvolved area of the injured knee during arthroscopy were isolated and cultured in the laboratory for 14 to 21 days. The cultured chondrocytes were then injected into the area of the defect. The defect was covered with a sutured periosteal flap taken from the proximal medial tibia. Evaluation included clinical examination according to explicit criteria and arthroscopic examination with a biopsy of the transplantation site. Results Patients were followed for 16 to 66 months (mean, 39). Initially, the transplants eliminated knee locking and reduced pain and s...

Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation

Autologous cultured chondrocyte transplantation was introduced in Sweden in 1987 for the treatment of large (1.5-12.0 cm2) full thickness chondral defects of the knee. The clinical, arthroscopic, and histologic results from the first 101 patients treated using this technique are reported in this study. Patients were assessed retrospectively using three types of endpoints: patient and physician derived clinical rating scales (five validated and two new); arthroscopic assessment of cartilage fill, integration, and surface hardness; and standard histochemical techniques. Ninety-four patients with 2- to 9-years followup were evaluable. Good to excellent clinical results were seen in individual groups as follows: isolated femoral condyle (92%), multiple lesions (67%), osteochondritis dissecans (89%), patella (65%), and femoral condyle with anterior cruciate ligament repair (75%). Arthroscopic findings in 53 evaluated patients showed good repair tissue fill, good adherence to underlying bone, seamless integration with adjacent cartilage, and hardness close to that of the adjacent tissue. Hypertrophic response of the periosteum or graft or both was identified in 26 arthroscopies; seven were symptomatic and resolved after arthroscopic trimming. Graft failure occurred in seven (four of the first 23 and three of the next 78) patients. Histologic analysis of 37 biopsy specimens showed a correlation between hyalinelike tissue (hyaline matrix staining positive for Type II collagen and lacking a fibrous component) and good to excellent clinical results. The good clinical outcomes of autologous chondrocyte transplantation in this study are encouraging, and clinical trials are being done to assess the outcomes versus traditional fibrocartilage repair techniques.

Two- to 9-year outcome after autologous chondrocyte transplantation of the knee.

Articular cartilage injuries ( Fig. 1 ) are common findings during arthroscopy 1 and diagnostic imaging of the joints 2,3. While there are many techniques for the treatment of cartilage injuries, not enough is known about which lesions need treatment or about the proper treatment modality for a particular lesion. More objective data regarding cartilage injuries and more accurate methods to evaluate the operative outcomes are required, especially since new procedures are becoming increasingly expensive. There are many published reports on the outcomes of total joint replacement based on clinical scores and radiographic evaluations. However, it has been quite difficult to interpret the reported results of the repair of focal cartilage defects as there is no universally accepted system to describe the lesions, the repair tissue, or the clinical symptoms for this category of patients. More studies on clinical articular cartilage resurfacing will appear in the future, making it important to develop common evaluation measurement tools and standards. The International Cartilage Repair Society (ICRS) was founded in 1997 and has been interested in developing a standardization system for the evaluation of cartilage injury and repair 4,5. A working group of the ICRS was established with the aim of developing a common, easy system for clinical and arthroscopic evaluation ( Table I ). Shortly thereafter, the Articular Cartilage Imaging Committee of the ICRS was created to assess the existing clinical imaging techniques, to recommend specific magnetic resonance imaging techniques for the assessment of articular cartilage 6, and to develop a standardized magnetic resonance imaging evaluation system for native and repaired cartilage ( Table I ). A state-of-the-art system for clinical cartilage evaluation and imaging assessment is presented below.



Fig. 1: 
A cartilage lesion on a femoral condyle, extending deep down to bone. Note that some calcified …

Evaluation of Cartilage Injuries and Repair

We evaluated the durability of autologous chondrocyte transplantation grafts in 61 patients treated for isolated cartilage defects on the femoral condyle or the patella and followed up for a mean of 7.4 years (range, 5 to 11). Durability was determined by comparing the clinical status at the long-term follow-up with that found 2 years after the transplantation. After 2 years, 50 of the 61 patients had good or excellent clinical results, and 51 of 61 had good or excellent results at 5 to 11 years later. Grafted areas from 11 of the patients were evaluated with an electromechanical indentation probe during a second-look arthroscopy procedure (mean follow-up, 54.3 months; range, 33 to 84); stiffness measurements were 90% or more of those of normal cartilage in eight patients. Eight of twelve 2-mm biopsy samples taken from these patients showed hyaline characteristics with safranin O staining and a homogeneous appearance in polarized light. Three fibrous and eight hyaline biopsy specimens stained positive to aggrecan and to cartilage oligomeric matrix protein. Hyaline-like specimens stained positive for type II collagen, and fibrous, for type I collagen. Autologous chondrocyte transplantation for the treatment of articular cartilage injuries has a durable outcome for as long as 11 years.

Mats Brittberg

Papers

Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation

Two- to 9-year outcome after autologous chondrocyte transplantation of the knee.

Evaluation of Cartilage Injuries and Repair

Autologous Chondrocyte Transplantation Biomechanics and Long-Term Durability

Bacterial cellulose as a potential scaffold for tissue engineering of cartilage