Trypsin Pre‐Treatment Combined With Growth Factor Functionalized Self‐Assembling Peptide Hydrogel Improves Cartilage Repair in Rabbit Model

Background: Microfracture augmentation can be a cost-effective single-step alternative to current cartilage repair techniques. Trypsin pretreatment combined with a growth factor–functionalized self-assembling KLD hydrogel (“functionalized hydrogel”) has been shown to improve overall cartilage repair and integration to surrounding tissue in small animal models of osteochondral defects. Hypothesis: Microfracture combined with trypsin treatment and a functionalized hydrogel will improve reparative tissue quality and integration as compared with microfracture alone in an equine model. Study Design: Controlled laboratory study. Methods: Bilateral cartilage defects (15-mm diameter) were created on the medial trochlear ridge of the femoropatellar joints in 8 adult horses (16 defects total). One defect was randomly selected to receive the treatment, and the contralateral defect served as the control (microfracture only). Treatment consisted of 2-minute trypsin pretreatment of the surrounding cartilage, subchondral bone microfracture, and functionalized hydrogel premixed with growth factors (platelet-derived growth factor and heparin-binding insulin-like growth factor 1). After surgery, all horses were subjected to standardized controlled exercise on a high-speed treadmill. Clinical evaluation was conducted monthly, and radiographic examinations were performed at 2, 16, 24, 32, 40, and 52 weeks after defect creation. After 12 months, all animals were euthanized. Magnetic resonance imaging, arthroscopy, gross pathologic evaluation of the joint, histology, immunohistochemistry, and biomechanical analyses were performed. Generalized linear mixed models (with horse as random effect) were utilized to assess outcome parameters. When P values were <.05, pairwise comparisons were made using least squares means. Results: Improved functional outcome parameters were observed for the treatment group, even though mildly increased joint effusion and subchondral bone sclerosis were noted on imaging. Microscopically, treatment resulted in improvement of several histologic parameters and overall quality of repaired tissue. Proteoglycan content based on safranin O–fast green staining was also significantly higher in the treated defects. Conclusion: Trypsin treatment combined with functionalized hydrogel resulted in improved microfracture augmentation. Clinical Relevance: Therapeutic strategies for microfracture augmentation, such as those presented in this study, can be cost-effective ways to improve cartilage healing outcomes, especially in more active patients.

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“…The hydrogel-assembling process was initiated by gently flowing sterile saline solution over the hydrogel. 31…”

Section: Treatmentmentioning

confidence: 99%

Microfracture Augmentation With Trypsin Pretreatment and Growth Factor–Functionalized Self-assembling Peptide Hydrogel Scaffold in an Equine Model

et al. 2021

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“…This procedure is referred to as AMIC and has shown favourable results in comparison to MST alone 5 years postsurgery. In addition to AMIC, several laboratories have developed technologies focused on augmenting MST to direct cell differentiation and produce hyaline-like cartilage (Kim et al, 2015;Madry et al, 2020;Miller et al, 2014;Morisset et al, 2007;Patel et al, 2020;Sennett et al, 2021;Zanotto et al, 2019). Only a few of these strategies have progressed beyond the preclinical testing stage (Sharma et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Marked differences in local bone remodelling in response to different marrow stimulation techniques in a large animal

Zlotnick¹,

Locke²,

Stoeckl³

et al. 2021

eCM

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Marrow stimulation, including subchondral drilling and microfracture, is the most commonly performed cartilage repair strategy, whereby the subchondral bone plate is perforated to release marrow-derived cells into a cartilage defect to initiate repair. Novel scaffolds and therapeutics are being designed to enhance and extend the positive short-term outcomes of this marrow stimulation. However, the translation of these newer treatments is hindered by bony abnormalities, including bone resorption, intralesional osteophytes, and bone cysts, that can arise after marrow stimulation. In this study, three different marrow stimulation approaches – microfracture, subchondral drilling and needle-puncture – were evaluated in a translationally relevant large-animal model, the Yucatan minipig. The objective of the study was to determine which method of marrow access (malleted awl, drilled Kirschner wire or spring-loaded needle) best preserved the underlying subchondral bone. Fluorochrome labels were injected at the time of surgery and 2 weeks post-surgery to capture bone remodelling over the first 4 weeks. Comprehensive outcome measures included cartilage indentation testing, histological grading, microcomputed tomography and fluorochrome imaging. Findings indicated that needle-puncture devices best preserved the underlying subchondral bone relative to other marrow access approaches. This may relate to the degree of bony compaction occurring with marrow access, as the Kirschner wire approach, which consolidated bone the most, induced the most significant bone damage with marrow stimulation. This study provided basic scientific evidence in support of updated marrow stimulation techniques for preclinical and clinical practice.

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“…This procedure is referred to as autologous matrix-induced chondrogenesis (AMIC), and has shown favorable results in comparison to MST alone 5 years post-surgery. In addition to AMIC, a number of laboratories have developed technologies focused on augmenting MST to direct cell differentiation and produce hyaline-like cartilage (Kim et al, 2015; Madry et al, 2020; Miller et al, 2014; Morisset et al, 2007; Patel et al, 2020; Sennett et al, 2021; Zanotto et al, 2019). Only a few of these strategies have progressed beyond the preclinical testing stage (Sharma et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Given the role of the subchondral bone in OA, it is likely that for augmented MST to reach its full potential, steps must be taken to address unintentional bony abnormalities that may arise from marrow access. This includes reports of bone resorption, intralesional osteophytes, and the formation of bone cysts (Cole et al, 2011;Zedde et al, 2016). These subchondral irregularities likely impede the translation of novel scaffolds and therapeutics (Sennett et al, 2021) and may also limit revision treatment options in the case that MST fails (Riff et al, 2020).…”

mentioning

confidence: 99%

“…Indeed, both small (1 mm) diameter awls (Orth et al, 2016) and small (1 mm) diameter K-wires were recently shown to improve MST outcomes in comparison to larger instrumentation (Eldracher et al, 2014). Others have suggested that small diameter (1 mm) holes that are deeper (9 mm depth) may preserve the underlying bone in comparison to more traditional larger (2 mm) and shallower (2 -4 mm) holes that can fragment and compact the bone (Chen et al, 2009;Zedde et al, 2016).…”

mentioning

confidence: 99%

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Marked differences in local bone remodeling in response to different marrow stimulation techniques in a large animal

Zlotnick

Locke

Stoeckl

et al. 2021

Preprint

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Marrow stimulation, including subchondral drilling and microfracture, is the most commonly performed cartilage repair strategy, whereby the subchondral bone plate is perforated to release marrow-derived cells into a cartilage defect to initiate repair. Novel scaffolds and therapeutics are being designed to enhance and extend the positive short-term outcomes of this marrow stimulation. However, the translation of these newer treatments is hindered by bony abnormalities, including bone resorption, intralesional osteophytes, and bone cysts, that can arise after marrow stimulation. In this study, three different marrow stimulation approaches, microfracture, subchondral drilling, and needle-puncture, were evaluated in a translationally relevant large animal model, the Yucatan minipig. The objective of this study was to determine which method of marrow access (malleted awl, drilled Kirschner wire, or spring-loaded needle) best preserved the underlying subchondral bone. Fluorochrome labels were injected at the time of surgery and 2 weeks post-surgery to capture bone remodeling over the first 4 weeks. Comprehensive outcome measures included cartilage indentation testing, histological grading, microcomputed tomography, and fluorochrome imaging. Our findings indicated that needle-puncture devices best preserved the underlying subchondral bone relative to other marrow access approaches. This may relate to the degree of bony compaction occurring with marrow access, as the Kirschner wire approach, which consolidated bone most, induced the most significant bone damage with marrow stimulation. This study provides basic science evidence in support of updated marrow stimulation techniques for preclinical and clinical practice.

show abstract

Trypsin Pre‐Treatment Combined With Growth Factor Functionalized Self‐Assembling Peptide Hydrogel Improves Cartilage Repair in Rabbit Model

Cited by 22 publications

References 32 publications

Microfracture Augmentation With Trypsin Pretreatment and Growth Factor–Functionalized Self-assembling Peptide Hydrogel Scaffold in an Equine Model

Microfracture Augmentation With Trypsin Pretreatment and Growth Factor–Functionalized Self-assembling Peptide Hydrogel Scaffold in an Equine Model

Marked differences in local bone remodelling in response to different marrow stimulation techniques in a large animal

Marked differences in local bone remodeling in response to different marrow stimulation techniques in a large animal

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