Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model

Abstract

Objective This study aimed to examine acellular extracellular matrix based hydrogels as potential therapies for treating peripheral artery disease (PAD). We tested the efficacy of using a tissue specific injectable hydrogel, derived from decellularized porcine skeletal muscle (SKM), compared to a new human umbilical cord derived matrix (hUC) hydrogel, which could have greater potential for tissue regeneration because of its young tissue source age. Background The prevalence of PAD is increasing and can lead to critical limb ischemia (CLI) with potential limb amputation. Currently there are no therapies for PAD that effectively treat all of the underlying pathologies, including reduced tissue perfusion and muscle atrophy. Methods In a rodent hindlimb ischemia model both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis (LASCA) to 35 days post-injection. Histology and immunohistochemistry were used to assess neovascularization and muscle health. Whole transcriptome analysis was further conducted on SKM injected animals on 3 and 10 days post-injection. Results Significant improvements in hindlimb tissue perfusion and perfusion kinetics were observed with both biomaterials. End point histology indicated this was a result of arteriogenesis, rather than angiogenesis, and that the materials were biocompatible. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue specific, SKM hydrogel more closely matched healthy tissue morphology. Short term histology also indicated arteriogenesis rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development. Conclusion These results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment.

Engineering an Injectable Muscle-Specific Microenvironment for Improved Cell Delivery Using a Nanofibrous Extracellular Matrix Hydrogel

“…1f). The complex microenvironment (multiple ECM proteins, proteoglycans, and potentially various growth factor binding sites) of the SkECM, which was previously demonstrated through quantitative mass spectrometry analysis, 8 could be contributing to an overall increase in cell viability under these stressed conditions.…”

Extracellular matrix hydrogels from decellularized tissues: Structure and function

“…Reverse phase high-performance liquid chromatography interfaced with tandem mass spectroscopy (LC-MS/MS) was used to determine the proteomic profile of pepsin-solubilized hydrogels by comparing the generated protein fragments to a protein data bank. Thus far, LC-MS/MS has been used to characterize liver [57], skeletal muscle [58], tendon [59], heart [55, 58, 60], kidney [61], pancreas [62] and umbilical cord [63] ECM hydrogels.…”

“…While injectability may be related to the viscoelastic properties (ECM pre-gel viscosity and gelation time), injectability has been independently confirmed in vitro and/or in vivo for heart [55, 60, 74–81], spinal cord [82], small intestine [26, 51], umbilical cord [63], skeletal muscle [63, 64, 83], tendon [59, 84], dermal [23], lung [49], liver [57], cartilage [70], urinary bladder [21, 22, 24, 82] and adipose [50, 67] ECM hydrogels with reported 18–27 gauge syringes or catheters. For example, porcine myocardial gel (6 mg/mL) was confirmed to be injectable through a 27 gauge catheter [75] , and then confirmed to be injectable via NOGA guided MyoSTAR catheter (27 gauge), which is the current gold standard delivery device used in cellular cardiomyoplasty procedures [75].…”

“…The viability of cells cultured on the surface of ECM hydrogels in vitro has been consistently shown for cell lines [23, 54, 63, 64, 70, 71, 83], primary cells [57, 63, 69, 71, 75, 83, 85], and stem cells [44, 49, 50, 73, 82, 86]. In addition, the innate bioactivity of soluble factors within the ECM has been demonstrated using in vitro culture with media supplemented with solubilized ECM to remove the influence of hydrogel structure on the function of cells.…”

“…In general, ECM hydrogels have been well-tolerated in a wide variety of in vivo applications. No adverse immune response was shown after ECM hydrogels were injected in the heart [55, 60, 75–81], fat [43, 45, 47, 50, 67], liver [57], brain [21, 22, 24] skeletal muscle [23, 63, 64, 83], tendon [26, 59, 84], spinal cord [82], lung [49], cartilage [70], or colon [51, 71], and these studies included both homologous and heterologous ECM hydrogels. The findings in vivo are consistent with in vitro studies that have shown the pepsin-digested ECM (“pre-gel”) promotes a regulatory (“M2-like”) macrophage activation state, which is associated with a constructive remodeling response in vivo [71, 90, 91].…”