The Effect of Subcutaneous Platelet-Rich Plasma Injection on Viability of Auricular Cartilage Grafts

Using Auricular Cartilage-fascia Composite Tissue Free Grafting Technique to Improve Cartilage Survival Outcomes

OBJECTIVES

Auricular cartilage graft has a wide range of applications in plastic and reconstructive surgery. However, there is still a risk of absorption of the grafts over time. Intrinsic postauricular fascia (IPF) with a rich vascular network may play an important role in the nutrition and repair of auricular cartilage. This study aimed to investigate the effect of IPF on the survival viability of free auricular cartilage grafts.

METHODS

24 auricular cartilages were obtained from 6 New Zealand white rabbits which were divided into the cartilage-fascia composite graft group (FC group, n=12) and the cartilage without fascia group (C group, n=12). Two groups of cartilage were implanted into each side of the subcutaneous pocket of the rabbit's dorsum. The rabbits were sacrificed after 3 months and all cartilage grafts were obtained. Macroscopic observation, histopathological staining, and biomechanical testing were performed on all specimens.

RESULTS

There were significant differences between the 2 groups regarding proliferating chondrocytes, apoptotic chondrocytes, vascularization, and matrix collagen. Compared to the auricular cartilage grafts without fascia, the auricular cartilage-fascia composite grafts had more neovascularization, proliferative chondrocytes, and type II collagen, with a homogeneous cartilage matrix and no obvious areas of heterogeneous staining. Young's modulus and ultimate tensile strength of cartilage were reduced in both groups compared to pretransplantation, but the composite graft group was superior to the fascia-free group.

CONCLUSIONS

Auricular cartilage-fascial composite tissue free graft could improve cartilage survival outcomes with higher viability and mechanical properties.

Diced Cartilage Techniques in Rhinoplasty

Diced cartilage has been widely applied in rhinoplasty, especially for segmental dorsal augmentation, with favorable outcomes over time. Various techniques were developed to increase both stability and viability of diced cartilage, including wrappings with non-blood material/blood products and changing the shapes of the diced cartilage, while the optimal technique is inconclusive. This article systematically reviews the current strategies of diced cartilage technique for rhinoplasty in the databases and emphasizes different wrapping materials. Free diced cartilage has a potential risk of gathering in certain regions and causing postoperative irregularities. Among non-blood wrapping materials, Surgicel is now rarely used due to severe foreign body reactions. The obvious drawbacks of fascia are donor site morbidity, inadequate quantity, and time-consuming. Although diced cartilage wrapped in tutoplast-processed fascia lata, AlloDerm, or esterified hyaluronic acid has achieved primary encouraging results, the increased inflammation raised controversies regarding their clinical use. Diced cartilage wrapped with blood products, such as platelet-rich fibrin or concentrated growth factor, achieved long-term reliable aesthetic results, and shaved cartilage and ultra-diced cartilage have recently shown satisfactory clinical outcomes, while further study is still needed. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Platelet-Derived Biomaterials Exert Chondroprotective and Chondroregenerative Effects on Diabetes Mellitus-Induced Intervertebral Disc Degeneration

Complications of diabetes mellitus (DM) range from acute to chronic conditions, leading to multiorgan disorders such as nephropathy, retinopathy, and neuropathy. However, little is known about the influence of DM on intervertebral disc degeneration (IVDD). Moreover, traditional surgical outcomes in DM patients have been found poor, and to date, no definitive alternative treatment exists for DM-induced IVDD. Recently, among various novel approaches in regenerative medicine, the concentrated platelet-derived biomaterials (PDB), which is comprised of transforming growth factor-β1 (TGF-β1), platelet-derived growth factor (PDGF), etc., have been reported as safe, biocompatible, and efficacious alternatives for various disorders. Therefore, we initially investigated the correlations between DM and IVDD, through establishing in vitro and in vivo DM models, and further evaluated the therapeutic effects of PDB in this comorbid pathology. In vitro model was established by culturing immortalized human nucleus pulposus cells (ihNPs) in high-glucose medium, whereas in vivo DM model was developed by administering streptozotocin, nicotinamide and high-fat diet to the mice. Our results revealed that DM deteriorates both ihNPs and IVD tissues, by elevating reactive oxygen species (ROS)-induced oxidative stress, inhibiting chondrogenic markers and disc height. Contrarily, PDB ameliorated IVDD by restoring cellular growth, chondrogenic markers and disc height, possibly through suppressing ROS levels. These data imply that PDB may serve as a potential chondroprotective and chondroregenerative candidate for DM-induced IVDD.

Platelet-Derived Biomaterials Inhibit Nicotine-Induced Intervertebral Disc Degeneration Through Regulating IGF-1/AKT/IRS-1 Signaling Axis

Apart from aging process, adult intervertebral disc (IVD) undergoes various degenerative processes. However, the nicotine has not been well identified as a contributing etiology. According to a few studies, nicotine ingestion through smoking, air or clothing may significantly accumulate in active as well as passive smokers. Since nicotine has been demonstrated to adversely impact various physiological processes, such as sympathetic nervous system, leading to impaired vasculature and cellular apoptosis, we aimed to investigate whether nicotine could induce IVD degeneration. In particular, we evaluated dose-dependent impact of nicotine in vitro to simulate its chronic accumulation, which was later treated by platelet-derived biomaterials (PDB). Further, during in vivo studies, mice were subcutaneously administered with nicotine to examine IVD-associated pathologic changes. The results revealed that nicotine could significantly reduce chondrocytes and chondrogenic indicators (Sox, Col II and aggrecan). Mice with nicotine treatment also exhibited malformed IVD structure with decreased Col II as well as proteoglycans, which was significantly increased after PDB administration for 4 weeks. Mechanistically, PDB significantly restored the levels of IGF-1 signaling proteins, particularly pIGF-1 R, pAKT, and IRS-1, modulating ECM synthesis by chondrocytes. Conclusively, the PDB impart reparative and tissue regenerative processes by inhibiting nicotine-initiated IVD degeneration, through regulating IGF-1/AKT/IRS-1 signaling axis.

Effect of Platelet-Derived Concentrated Growth Factor on Single-Layer, Multi-Layer, and Crushed Onlay Cartilage Grafts

BACKGROUND

The main concern with utilizing cartilage grafts to achieve structural integrity and volume restoration is the loss of volume over time and their unpredictable viability. Preservation of the volume of cartilage grafts is necessary to ensure their long-term success.

OBJECTIVES

The main aim of this study was to investigate the effect of concentrated growth factor (CGF) sheet on single-layer, multi-layer, and crushed block cartilage grafts.

METHODS

Cartilage grafts obtained from the ears of rabbits were prepared in 3 different forms: single-layer, triple-layer, and crushed. After measuring the weight and thickness of the cartilage grafts, the grafts in the experimental group were wrapped with the prepared autologous CGF. These cartilage grafts were placed in subcutaneous pouches created on the backs of the rabbits. After 4 months, the rabbits were killed. The weight and thickness of the cartilage grafts were measured and the cartilage viability and peripheral changes were examined microscopically.

RESULTS

The percentage changes in the weights and thicknesses of the single-layer, multi-layer, and crushed cartilage grafts wrapped with CGF were found to be statistically significantly lower than in the control group. When the cartilage viability and changes in peripheral tissue were evaluated, CGF-wrapped cartilage groups did not achieve statistically significantly better scores than the untreated control groups.

CONCLUSIONS

In cases planned to receive a block cartilage graft, especially if graft resorption is not desired or should be minimized, wrapping the graft with autologous CGF is a feasible option.

Effect of Autologous Platelet-Rich Plasma Gel on Skin Flap Survival

BACKGROUND Skin flap grafting is one of the most common tissue transplantations for wound repair and organ reconstruction. Thus, improving the survival rate of the transplanted skin flap is important. Platelet-rich plasma (PRP) is an autologous platelet concentrate obtained from whole blood. It has been widely used in repairing tissue defects. Considering that the PRP gel has similar biological characteristics, this study used PRP gel for skin flap transplantation. MATERIAL AND METHODS PRP gel from Sprague-Dawley (SD) rats was prepared and the growth factor concentration was determined. A rat skin flap model was established to evaluate the survival rate of skin flap. Morphologic evaluation was also done. RESULTS We found that the PRP gel increased the survival rate of the skin flap. In addition, it reduces the inflammation response in skin flap transplantation and has better effects in terms of generating new soft tissue. CONCLUSIONS The effectiveness PRP gel in skin flap transplantation is satisfactory. The possible mechanisms by which PRP gel promotes the survival of the skin flap includes platelets, growth factors, immune activity factor, and fibrin. PRP could be a new clinical method for promoting skin flap survival.

The Role of Platelet-Rich Plasma in Cartilage Pathology: An Updated Systematic Review of the Basic Science Evidence

PURPOSE

To review the basic science studies on platelet-rich plasma (PRP) for cartilage and determine whether there has been an improvement in methodology and outcome reporting that would allow for a more meaningful analysis regarding the mechanism of action and efficacy of PRP for cartilage pathology.

METHODS

The PubMed/MEDLINE and EMBASE databases were screened in May 2017 with publication dates of January 2011 through May 2017 using the following key words: "platelet-rich plasma OR PRP OR autologous conditioned plasma (ACP) OR ACP AND cartilage OR chondrocytes OR chondrogenesis OR osteoarthritis OR arthritis." Two authors independently performed the search, determined study inclusion, and extracted data. Data extracted included cytology/description of PRP, study design, and results.

RESULTS

Twenty-seven studies (11 in vitro, 13 in vivo, 3 in vitro and in vivo) met the inclusion criteria and were included in the study. All of the studies (100%) reported the method by which PRP was prepared. Two studies reported basic cytologic analysis of PRP, including platelet, white blood cell, and red blood cell counts (6.7%). Nine studies reported both platelet count and white blood cell count (30.0%). Twelve studies reported platelet count alone (40.0%). Nine studies (30.0%) made no mention at all as to the composition of the PRP used. PRP was shown to increase cell viability, cell proliferation, cell migration, and differentiation. Several studies demonstrated increased proteoglycan and type II collagen content. PRP decreased inflammation in 75.0% of the in vitro studies reporting data and resulted in improved histologic quality of the cartilage tissue in 75.0% of the in vivo studies reporting data.

CONCLUSIONS

Although the number of investigations on PRP for cartilage pathology has more than doubled since 2012, the quality of the literature remains limited by poor methodology and outcome reporting. A majority of basic science studies suggest that PRP has beneficial effects on cartilage pathology; however, the inability to compare across studies owing to a lack of standardization of study methodology, including characterizing the contents of PRP, remains a significant limitation. Future basic science and clinical studies must at a minimum report the contents of PRP to better understand the clinical role of PRP for cartilage pathology.

CLINICAL RELEVANCE

Establishing proof of concept for PRP to treat cartilage pathology is important so that high-quality clinical studies with appropriate indications can be performed.