Xiphoid process-derived chondrocytes: a novel cell source for elastic cartilage regeneration.

Reconstruction of elastic cartilage requires a source of chondrocytes that display a reliable differentiation tendency. Predetermined tissue progenitor cells are ideal candidates for meeting this need; however, it is difficult to obtain donor elastic cartilage tissue because most elastic cartilage serves important functions or forms external structures, making these tissues indispensable. We found vestigial cartilage tissue in xiphoid processes and characterized it as hyaline cartilage in the proximal region and elastic cartilage in the distal region. Xiphoid process-derived chondrocytes (XCs) showed superb in vitro expansion ability based on colony-forming unit fibroblast assays, cell yield, and cumulative cell growth. On induction of differentiation into mesenchymal lineages, XCs showed a strong tendency toward chondrogenic differentiation. An examination of the tissue-specific regeneration capacity of XCs in a subcutaneous-transplantation model and autologous chondrocyte implantation model confirmed reliable regeneration of elastic cartilage regardless of the implantation environment. On the basis of these observations, we conclude that xiphoid process cartilage, the only elastic cartilage tissue source that can be obtained without destroying external shape or function, is a source of elastic chondrocytes that show superb in vitro expansion and reliable differentiation capacity. These findings indicate that XCs could be a valuable cell source for reconstruction of elastic cartilage.

Fibrin glue: a scaffold for cellular-based therapy in a critical-sized defect.

PURPOSE: Cartilage-based treatments have vast applications in plastic and reconstructive surgery, especially craniofacial constructs. Current techniques in craniofacial cartilage reconstructions greatly rely on autologous donor site harvest. Whole cartilage grafts are wrought with complications of warping, resorption, extrusion, and donor site morbidity. Percutaneous delivery of expanded chondrocytes would have the potential to expand a small quantity of autologous cells to deliver cell therapy. To deliver chondrocytes effectively, there must be a reliable medium in which chondrocytes can be kept. The purpose of this work is to highlight the utility of fibrin glue sealant, Evicel, as a suitable chondrocyte carrier in the treatment of a critical-sized defect model of nonarticular cartilage previously developed in our laboratory. METHODS: Athymic rats were separated into 2 groups: fibrin glue (n = 3) and fibrin glue + rat chondrocytes (n = 6). The animals with an empty defect were used to ensure that they responded normally to the procedure. All animals received a 3-mm full-thickness xiphoid cartilage defect characterized previously as a critical-sized defect in our laboratory (Moyer HR, Wang Y, Farooque T, et al. Tissue Eng Part A. 2010;16:2321-2330). A control animal received no xiphoid defect creation procedure. The fibrin glue group was treated with 0.5 mL of fibrin glue placed directly into the 3-mm defect. The fibrin glue/rat chondrocyte group received a mixture of 1 × 10 resting zone chondrocytes mixed with 0.5 mL of fibrin glue. Rats were euthanized at 5 weeks (35 days) and their xiphoid cartilages harvested. The xiphoids were analyzed with morphometrics through histology and microcomputed tomography. RESULTS: In the fibrin glue vehicle group, there was minimal evidence of wound healing. Xiphoid defects treated with resting zone chondrocytes in a fibrin glue carrier were significantly smaller (P = 0.002) at harvest and had significantly more glycosaminoglycan content on microcomputed tomography analysis. Thus, there was significant healing in the chondrocyte/fibrin glue group. CONCLUSION: Human fibrin sealant is an effective chondrocyte carrier and retains viable cells. Treatment of a nonarticular critical-size defect with resting zone chondrocytes embedded in a fibrin glue polymer demonstrates tissue healing.

Accumulation of calcium in human common iliac artery, aortic valve, xiphoid process, costal cartilage, posterior longitudinal ligament, trigeminal nerve, and rib accompanied by increase of magnesium.

To examine whether an accumulation of Ca in the tissues was accompanied by an increase of Mg, the authors investigated the relationships between Ca and Mg contents in the common iliac arteries, aortic valves, xiphoid processes, costal cartilages, posterior longitudinal ligaments, trigeminal nerves, and ribs by inductively coupled plasma-atomic emission spectrometry. After the ordinary dissections by medical students were finished, the common iliac arteries, aortic valves, xiphoid processes, bilateral the fourth costal cartilages, posterior longitudinal ligaments between the fourth and fifth cervical vertebrae, trigeminal nerves, and bilateral the sixth ribs were resected from the subjects and elements were determined. It was found that there were extremely significant direct correlations between Ca and Mg contents in all of the common iliac arteries, aortic valves, costal cartilages, posterior longitudinal ligaments, and trigeminal nerves, whereas there were significant direct correlations in both the xiphoid processes and ribs. As for the tissues containing Ca higher than 20 mg/g, the average mass ratios of Mg/Ca were similar among the seven tissues. As Ca increased in all of the common iliac arteries, aortic valves, xiphoid processes, costal cartilages, posterior longitudinal ligaments, trigeminal nerves, and ribs, Mg increased simultaneously in the seven tissues.

Perichondrial localization of ETA receptor in rat tracheal and xiphoid cartilage and in fetal rat epiphysis.

Autoradiographic studies using 125I-labeled endothelin-1 (ET-1) on sections of rat cartilage tissues, including the trachea, xiphisternum, and fetal rat epiphysis, revealed dense localization of endothelin receptors in the perichondrium. In contrast, the binding of ET-1 was not detected in the chondrocytes, cartilage matrix, and other connective tissues of the cartilage tissues tested. The perichondrial binding of 125I-ET-1 was completely abolished with BQ-123 [an endothelin receptor subtype A (ETA) antagonist] but not with BQ-3020 (an ETB agonist), and we demonstrated the perichondrial localization of ETA receptors. [3H]thymidine incorporation in vitro was significantly increased in rat xiphoid cartilage tissues exposed to ET-1. These findings suggest that the ET-1/ETA receptor system plays an important role in regulating cartilage metabolism and endochondral bone formation.

Structural and metabolic changes characterizing the aging of various cartilages in mice.

It is well documented that various organs and tissues in the body show a differential, non-homogeneous pattern of development and aging. The present study evaluates some of the morphological and metabolic changes characterizing the aging of different types of cartilages in normal male mice. Representatives of hyaline, fibrous, articular and elastic types of cartilage were obtained from animals ranging from 1 week to 1 year of age. Our determinations included the following: total body and organ weights, proteins and DNA concentrations, [3H]leucine and [35S]sulfate uptake. The biochemical assays were accompanied by morphological examinations of corresponding tissue specimens. This investigation clearly indicates that the growth and maturational activities of the various cartilages examined attained their completion at a very early stage of life (1-3 months postnatally). Thereafter, a phase of steady state prevails, followed by a gradual but continuous decline in the various metabolic activities. The morphological findings illustrate the nature of the age-related structural changes. The present findings indicate that a skeletal tissue such as cartilages of various types, tends to age early during the lifespan of the animal.

Quantitative morphological and histochemical study of the xiphisternal cartilage and its intracellular lipids in the guinea-pig.

The xiphisternal cartilages of newborn, suckling, immature and adult guinea-pigs were divided into twelve regions in a study of their histology and intracellular lipid content. Histochemical methods were employed, and the observations quantified using a semi-automatic image analyser. In general, triglyceride content increases with age and is lower in surface layers and in distal and lateral regions than in deep layers and proximal and medial regions. Phospholipids, on the other hand, diminish with age and are most abundant in surface layers and in distal and lateral regions. The nature and quantity of these lipids in the various regions and layers into which the cartilages were subdivided has been related to the size of the lacunae in which the cells lie.