Porcine Dermis-Derived Collagen Membranes Induce Implantation Bed Vascularization Via Multinucleated Giant Cells: A Physiological Reaction?

This figure shows histological images of the blank biomaterials prior to implantation. (a) shows a cross-section through the body of the Mucoderm matrix (MD = double head arrow) with its fiber distribution and microstructure (hematoxylin and eosin [H&E], magnification ×40, scale bar = 100 μm). (b) shows the enclosed fatty tissue-like islands (black arrows) and the enclosed vessel skeletons (blue arrows) within the matrix (MD; H&E, magnification ×200, scale bar = 10 μm). (c) and (d) show the enclosed vessel skeletons (blue arrow heads) that exhibit histological signs of muscle ring-like assembly around their lumina (MD = Mucoderm matrix) (c: sirius stain, magnification ×200, scale bar = 10 μm; d: Masson Goldner staining of collagen, magnification ×400, scale bar = 10 μm). (e) and (f) show the morphology and microstructure of the Collprotect membrane (CP = double head arrows), which exhibits more consistently arranged collagen fibers without any signs of other tissue structures (H&E, e: magnification ×100, scale bar = 100 μm; f: magnification ×200, scale bar = 10 μm).

This figure shows the tissue reactions and the integration behavior of the Mucoderm matrix (MD) at days 3 (a and b), 10 (c and d) and 15 (e and f) after implantation in subcutaneous connective tissue (CT) of the CD-1-mice. On days 3, 10, and 15 after implantation (a, c, and e) a thin wall of mononuclear cells (black arrow heads) was observed at the surfaces of the membranes (MD), while a comparatively low number of cells was found within the body of the matrix (green arrow heads; CT = connective tissue; a: hematoxylin and eosin [H&E], c: Movat pentachrome stain, e: Movat pentachrome stain; magnifications ×400; scale bars = 10 μm). Within this time frame the matrix remained stable within the subcutaneous connective tissue (CT) and no signs of tissue ingrowth were observable (b, d, and f). The described fatty tissue-like islands (black arrows) and the vessel skeletons (blue arrow heads) were invaded by single mononuclear cells at these time points (b: H&E; d: Movat pentachrome stain; f: sirius stain, magnifications ×100; scale bars = 100 μm).

This figure shows the tissue reaction (a and a1) and the integrative behavior (b, c, and d) of the Mucoderm matrix (MD) at day 30 after implantation in the subcutaneous connective tissue (CT) of the CD-1-mice. (a) and (a1) show that mainly mononuclear cells (black arrow heads) and a few multinucleated giant cells (red arrow heads) and many vessels (red arrows in a) were located at the surface of the Mucoderm matrix (MD) at day 30 after implantation (CT = connective tissue). Note that the fibers of the Mucoderm matrix (MD) are surrounded by numerous superficial and deeper mononuclear cells (black/green arrow heads). Additionally, multinucleated giant cells (red arrow head in a1) have started to invade the matrix (azan stain, a: magnification ×200, a1: magnification ×400, scale bars = 10 μm). (b) shows that the Mucoderm matrix (MD = double arrow) was still detectable within the subcutaneous CT without signs of breakdown. Note that the lumina of the preexisting vessel skeletons (blue arrow heads) and the former fatty tissue-islands (black arrows) were filled by connective tissue (sirius stain, b: magnification ×100, scale bar = 100 μm). (c) and (d) show the vessel skeletons that contained CT surrounded by mononuclear cells (black arrow heads) and microvessels (red arrows), while the body of the matrix only contained a few mononuclear cells (green arrow heads) at this later time point (c: hematoxylin and eosin, magnification ×200, scale bar = 100 μm; d: azan stain, magnification ×400, scale bar = 10 μm).

This figure shows the tissue reactions to the Collprotect membrane (CP). (a) and (b) show that a thin layer of mononuclear cells (black arrow heads in a) and small-sized vessels (read arrows in a) were located at the surface of the membrane (CP) at day 3 after implantation. The membrane (CP = double arrow in b) was detectable within the subcutaneous connective tissue (CT) and shows no signs of tissue ingrowth (CT = connective tissue; hematoxylin and eosin [H&E]; a: magnification ×400, scale bar = 10 μm; b: magnification ×100, scale bar = 100 μm). (c) and (d) show the tissue reaction to the Collprotect membrane (CP = double arrow) at day 10 after implantation. The surface of the membrane was still covered by a thin wall of mononuclear cells (black arrow heads in c), and few cells invaded the body of the membrane at this time point (green arrow heads in c). The membrane (CP = double arrow in d) was still detectable with the CT without any change in its integrity (c: Movat pentachrome stain, magnification ×400, scale bar = 10 μm; d: sirius stain, magnification ×100, scale bar = 100 μm). (e) and (f) show the tissue reaction to the Collprotect membrane (CP = double arrow) at day 15 after implantation. The membrane surfaces were covered by mono- and multinuclear cells (black/red arrow heads in e), while the membrane (CP = double arrow in F) was still observable in the CT without loss of its volume stability. At this time point more cells have started to penetrate the membrane in its superficial regions (green arrow heads in e; e: Movat pentachrome stain, magnification ×400, scale bar = 10 μm; f: H&E, magnification ×100, scale bar = 100 μm). (g) and (h) show the tissue reaction to the Collprotect (CP = double arrow) at day 30 after implantation. Complex tissue threads with mono- and multinucleated cells (black/red arrow heads in g), cells penetrating the membrane (green arrow heads in g), and vessels (red arrows in g) have started to invade its superficial and deeper regions, while the membrane (CP = double arrows in h) maintained its integrity (CT = connective tissue; g: Azan-stain, magnification ×400, scale bar = 10 μm; h: sirius stain, magnification ×100, scale bar = 100 μm).

This figure shows the results of the histomorphometrical thickness measurements of the Mucoderm matrix (a and b) and the Collprotect membrane (c and d). (a) Membrane thickness of the Mucoderm matrix was significantly reduced on day 30 compared to day 3 (*P < .05). (b) The percent thickness of the Mucoderm matrix did not significantly reduce over the study time. (c) Membrane thickness of the Collprotect membrane was significantly reduced between day 15 and day 3, between day 30 and day 3, between day 30 and day 10 (***P < .001) and between day 15 and day 10 (**P < .01). (d) The comparison of the percent thickness showed also a significant decrease starting with day 15 (*P < .05) and remaining at day 30 (**P < .01) as well as between day 10 and 15 (**P < .01) and day 10 and 30 (***P < .001). Decrease of membrane thickness is stated as significant if P-values were less than .05 (*P < .05), and highly significant if P-values were less than .01 (**P < .01) or less than 0.001 (***P < .001).

This figure shows the results of the histomorphometrical measurements of the numbers of multinucleated giant cells (a), vessel density (b), and vascularization percent (c). Inter- (*) and intraindividual (•) significant differences were marked if P-values were less than 0.05 (*/• P < .05), and highly significant if P-values were less than .01 (**/•• P < .01) or less than .001 (***/••• P < .001).