Table 1.
A summary of experimental groups and the number of rabbits in the ACA and control groups.
Fig 1.
Representative computer tomography images of the uninjured (A) and injured (C, arrow) bones. Panels B (uninjured bone) and D (injured bone) indicate subchondral bone regions analyzed here to determine the extent of mineralization in the injured area (C&D).
Fig 2.
The appearance of the surface of uninjured (A) and injured (B) femoral condyles after twelve weeks of healing. The white arrow in B indicates the site of the osteochondral defect (OCD) made during the initial surgery. Please note the presence of the pannus-like tissue (black arrows) covering the femoral surface of the injured leg (B). C, An osteochondral plug (OCP) that encompasses the site of injury seen in panel B. A tool used to remove the plug is also indicated.
Table 2.
A summary of differences in the trajectories of changes in serum hydroxyproline (HP), the C-terminal propeptide of procollagen I (CP), and cross-linked telopeptides (XL) measured between the ACA group and the CA group during the 8-week treatment period.
Fig 3.
A graphic representation of the changes in the concentration of hydroxyproline (HP), the C-terminal propeptide (CP), and cross-linked telopeptides (XL) at indicated time points; the square symbols (■) represent the ACA-treated group, and the circle symbols (●) represent the control group.
The geometric means (GMs) of analyzed parameters and 95% confidence intervals are presented.
Table 3.
Significance of changes in serum concentrations of hydroxyproline (HP), the C-terminal propeptide of procollagen I (CP), and cross-linked telopeptides (XL).
These changes were measured within the ACA group and within the CA group across various time points.
Fig 4.
Histological quantification of various populations of picrosirius-stained collagen fibrils formed within injured posterior capsules (PCs).
A, Samples of the PCs from uninjured (Un) and injured (In) knee joints of rabbits treated with control antibody (CA). B, Samples of the PCs from uninjured (Un) and injured (In) knee joints of the rabbits treated with the ACA. C&D, Corresponding graphs depict the percentages, with standard deviations in parentheses, of the green birefringence (GB), yellow birefringence (YB), and red birefringence (RB) subpopulations of collagen fibrils observed with the use of a polarized light microscope in the 8wk and 12wk groups. Bars = 100 μm.
Table 4.
Analysis of differences between specific groups of collagen fibrils, defined by specific birefringence, observed in uninjured and injured posterior capsules (PCs) isolated from the ACA-treated or control rabbits.
Fig 5.
A histological assay of the pannus-like scar tissue formed in an osteochondral defect (delineated).
The site of injury was stained with H&E (A) and with collagen-specific picrosirius red (B&C). The picrosirius red-stained samples were observed in normal light (B) and polarized light (C). Fibrotic tissue (FT), bone (B), and fragments of the articular cartilage (AC) are indicated. D&E, A summary of measurement of the percentages of the green birefringence (GB) fibrils, yellow birefringence (YB) fibrils, and red birefringence (RB) fibrils formed in the CA-treated and the ACA-treated rabbits. Corresponding segments of the bars include the means and standard deviations (in parentheses). Data for the 8wk and the 12wk groups are presented. Bars = 1 mm.
Table 5.
Significance of differences between the content of specific groups of collagen fibrils defined by the green (GB), yellow (YB), and red (RB) birefringence.
The fibrils were observed in the osteochondral defects in the CA-treated and the ACA-treated rabbits.
Fig 6.
A graphic representation of the FTIR-based assays of the relative amount of collagen and the maturity of collagen cross-links in the scar tissue formed within injured posterior capsules of control (CA) and the ACA-treated rabbits.
Results for the 8wk and the 12wk groups are presented. The graphs show geometric means (GMs) with 95% confidence intervals. Asterisks indicate groups with statistically significant differences of the means. The graph shows the relative collagen content calculated as the sulfated glycosaminoglycans (GAGs)/collagen and the total protein/collagen ratios. Consequently, the smaller the ratios, the higher relative collagen content. The ratios were calculated based on the areas of the spectral peak corresponding to the sulphated GAGs (centered around 1064 cm-1) and the spectral peak corresponding to collagen (centered around 1338 cm-1). To corroborate these measurements, the relative amount of collagen was also calculated based on the ratios of the spectral peak corresponding to the total proteins, represented by the amide II peak (centered around 1549 cm-1) and the spectral peak corresponding to collagen. The maturity of collagen cross-links was expressed as the ratio of the area of the spectral peak corresponding to the mature trivalent PYR cross-link (centered around 1660 cm-1) and immature divalent deDHLNL cross-link (centered around 1690 cm-1). Hence, the higher the PYR/deDHLNL ratio the more mature collagen cross-links. Also, see S1 Table in S1 File.
Fig 7.
A graphic representation of the FTIR-based assays of the relative amount of collagen and the maturity of collagen cross-links in the scar tissue formed in the OCDs of the CA-treated and the ACA-treated rabbits.
Results for the 8wk and the 12wk groups are presented. The graphs present GMs with 95% confidence intervals. Asterisks indicate groups with statistically significant differences of means. The graph shows the relative collagen content calculated as the GAG/collagen and the total protein/collagen ratios. Hence, the smaller the ratios, the higher relative collagen content. The ratios were calculated based on the areas of the spectral peak corresponding to the sulphated GAGs (centered around 1064 cm-1) and the spectral peak corresponding to collagen (centered around 1338 cm-1). To corroborate these measurements, the relative amount of collagen was also calculated based on the ratios of the spectral peak corresponding to the total proteins, represented by the amide II peak (centered around 1549 cm-1) and the spectral peak corresponding to collagen. The maturity of collagen cross-links was expressed as the ratio of the area of the spectral peak corresponding to the mature trivalent PYR cross-link (centered around 1660 cm-1) and immature divalent deDHLNL cross-link (centered around 1690 cm-1). Thus, the higher the PYR/deDHLNL ratio, the more mature the collagen cross-links. See also S1 Table in S1 File.
Table 6.
Analysis of differences between relative collagen contents and the maturity of collagen-cross-links in scar tissues formed in the PCs and osteochondral defects (OCD) in the CA-treated ACA-treated rabbits.
Table 7.
Summaries of tests to determine the ACA’s effects on the flexion contracture and parameters defining the quality of healing of the PTs (stress and Young’s modulus) and subchondral bone defects (Bv/Tv and BMD)a.