**3.4 Platelet-rich plasma (PRP)**

Platelets play a fundamental role in hemostasis and are a natural source of growth factors. More than 30 growth factors have been identified in PRP; among them, the following six growth factors play an important role in cartilage

**Figure 1.**

*Scheme of preparation of P-PRP and L-PRP from whole blood using five steps.*

regeneration. They are TGF-β1, platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), insulin-like growth factor 1 (IGF-1), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) [67, 68].

The concentration of platelet in PRP used for cartilage repair should be two to three times higher than that of baseline [69]. PRP can be prepared by the following five procedures (**Figure 1**). **Step 1:** blood (9 parts) is added into 3.8% sodium citrate solution (1 part) in a centrifuge tube and centrifuged at 500 g for 5 min to obtain three layers. **Step 2:** The supernatant at the top layer is transferred into a new tube, which is called as platelets-containing plasma, and the middle layer is transferred into another new tube, which is called leukocytes-containing plasma. **Step 3:** The platelets-containing plasma is centrifuged at 2000 g for 5 min to separate platelet-poor plasma (PPP) from the platelet pellet. **Step 4:** The platelet pellet is resuspended with appropriate amount of PPP to make pure PRP (P-PRP). **Step 5:**  The leukocytes-containing plasma is mixed with platelet pellet and resuspended with appropriate amount of PPP to make leukocytes-containing PRP (L-PRP). Both P-PRP and L-PRP can be used for cartilage tissue engineering [70].

## **4. Bioactive molecules used for cartilage tissue engineering**

Bioactive molecules used in cartilage tissue engineering include two kinds of materials: one is small molecular weight bioactive compound and the other one is high molecular weight materials including some nature biomaterials and synthetic polymers. Both of them play critical role in cartilage tissue engineering.

#### **4.1 Kartogenin (KGN)**

Kartogenin (KGN), a small heterocyclic molecule, has been discovered to enhance chondrogenic differentiation of human MSCs by regulating the *Current Tissue Engineering Approaches for Cartilage Regeneration DOI: http://dx.doi.org/10.5772/intechopen.84429*

CBFbeta-RUNX1 transcriptional program [71, 72]. Animal studies have shown that KGN can promote rabbit meniscus regeneration [73] and wounded rat enthesis repair [70, 74]. *In vitro* and *ex vivo* experiments showed that KGN can reduce nucleus pulposus cell degeneration induced by interleukin-1beta (IL-1β) and tumor necrosis factor-alpha [75]. More recent studies indicated that KGN inhibited pain behavior, chondrocyte inflammation, and attenuated osteoarthritis progression in mice [76]; enhanced collagen organization and mechanical strength of the repaired enthesis of mouse rotator cuff [77]; and induced chondrogenic differentiation of dental pulp stem cells [78].

These findings invigorate research into small-molecule therapy and regenerative medicine for cartilage diseases. It also provides new insights into the control of chondrogenesis that may ultimately lead to a stem cell-based therapy for osteoarthritis (OA). KGN and other structurally related small molecules that can promote selective differentiation of MSCs into chondrocytes may prove to be extremely useful for improving the outcome of cell-based therapy by stimulating endogenous mechanisms for repair of damaged cartilage, thus enhancing the joint's intrinsic capacity for cartilage regeneration [79].

#### **4.2 Simvastatin**

Simvastatin is a kind of HMG-CoA reductase inhibitor, which is widely used therapeutically to reduce morbidity and mortality in patients with hyperlipidemic cardiovascular disease [80]. In addition to lowing low-density lipoprotein (LDL) cholesterol, statins have broad-range pleiotropic effects, including antiinflammatory effects, which could exert an effect on synovium and cartilage [81]. Animal studies found that simvastatin markedly inhibited not only developing but also established collagen-induced arthritis [82]. Simvastatin inhibited the IL-6 and TNF-α production of human chondrocytes and cartilage explants in a concentration-dependent manner. Higher concentrations of simvastatin decreased nitric oxide (NO) production in both of human chondrocytes and cartilage explants [83]. Statin treatment has also been shown to positively regulate components of the extracellular matrix in a rabbit OA model [84]. More studies have shown that local application of simvastatin enhanced tendon-bone interface healing in rabbits [85]. These studies have shown that the effect of simvastatin on articular chondrocytes may provide novel insight regarding the role of cholesterol homeostasis and signaling during cartilage development.

#### **4.3 Biomaterial scaffolds for cartilage tissue engineering**

Biomaterial scaffolds play an important role in cartilage tissue engineering, which act as a carrier to deliver the cells and bioactive molecules to the damaged tissue areas and also work as a template for tissue regeneration, to guide the growth of new tissue.

There are two groups of biomaterial scaffolds used for cartilage tissue engineering. They are synthetic polymers and natural polymers. Commonly used natural materials in cartilage repair are agarose, alginate, chitosan, collagen, fibrin, and hyaluronan.

 Agarose is a galactose polymer, which is suitable for cell encapsulation, especially for chondrocytes. When the ADSCs were cultured in agarose, they were differentiated into chondrocytes as evidenced by upregulation of the production of glycosaminoglycan (GAG) [86]. Moreover, dynamically loaded cell-seeded agarose hydrogel provided better graft tissues in a repair model of full thickness defects in rabbit joint cartilage [87]. PRP combined with agarose as a bioactive scaffold has shown to enhance cartilage repair [88].

Another extensively studied natural scaffold used for cartilage tissue engineering is alginate, which is a polysaccharide extracted from brown algae. Generally, alginate is hydrophilic and water-soluble, thickening in neutral conditions, which is of great importance for *in situ* hydrogel formation [89]. The good gelling properties of alginate-based scaffolds allowed them to be used as an injectable scaffold for the damaged cartilage repair. Human dental pulp stem cells were cultured in 3% alginate hydrogel and implanted in a rabbit damaged cartilage area. Three months after surgery, significant cartilage regeneration was observed [90]. More studies have been done by mixing the cells or/and growth factors with alginate solution to form gel microspheres in an isotonic CaCl2 solution (**Figure 2**). The findings have shown that the cells are distributed homogeneously inside the gel microspheres. Those cell-containing alginate beads can be used as chondrogenesis-promoting scaffolds for cartilage regeneration [91, 92].

Chitosan is another natural polysaccharide extracted from crustacean shells, particularly from shrimps and crabs. Chitosan contains glucosamine and hyaluronic acid (HA), which are basic components of the native cartilage. Therefore, chitosan is widely used for cartilage tissue engineering. The recent studies have shown that chitosan-hyaluronic acid hydrogel promoted wounded cartilage healing in a rabbit model [93, 94].

Collagen is a main component of the extracellular matrix (ECM) of chondrocytes. Collagen gel has been widely used as substrates for articular cartilage substitutes [95, 96]. Injectable type II collagen gel has been used to treat full-thickness articular cartilage defects [97]. Clinical study has demonstrated that collagen gel can be used to replace cartilage and subchondral bone [98].

Fibrin hydrogels used for articular cartilage repair has been well documented by a review paper [99]. It has been reported that chondrocytes survived in the fibrin gel and enhanced their synthetic activity as evidenced by the increase of the production of GAG and collagen type II [100]. Human fibrin hydrogels have been approved by the Food and Drug Administration (FDA) for cartilage tissue engineering [101].

 Hyaluronan is a main component of native cartilage. Similarly to the other native biomaterial scaffold, hyaluronan is the most widely used scaffold for cartilage tissue engineering. The studies have shown that hyaluronan upregulated collagen II expression and downregulated collagen I expression in human MSCs when they were cultured in hyaluronan gel [102].

Although bioactive natural scaffolds have very good biocompatibilities, their mechanical properties still need to be improved. In addition to natural bioactive scaffolds, synthetic materials provide good mechanical properties suitable for cartilage tissue engineering. These synthetic polymers are either used alone or combined with natural biomaterials for cartilage research.

#### **Figure 2.**

*The intermolecular network of alginate molecules is formed in calcium chloride solution. Alginate can be dissolved with sodium chloride (left image), but cross-linked each other in calcium ions-containing solution to form hydrogel (right image).*

#### *Current Tissue Engineering Approaches for Cartilage Regeneration DOI: http://dx.doi.org/10.5772/intechopen.84429*

The most famous synthetic polymers for cartilage regeneration are polylactic acid (PLA), polyglycolic acid (PGA), and their copolymer polylactic-co-glycolic acid (PLGA). These polymers have a beneficial range of mechanical characteristics and high biocompatibility. Owing to the fact that PLA-PGA polymers have been successfully used in the clinics including sutures, screws, and pins [103–105], they are also used for articular cartilage defect repair in rabbits [106] and meniscal lesion repair in dogs [107]. Currently, two PLA-based scaffolds have been clinically used for cartilage repair: one is BioSeed ®-C and the other one is TRUFIT CB™. The PLA-based polymer scaffolds have shown significant improvement in patient outcomes for the treatment of post-traumatic OA and focal degenerative cartilage defects [108, 109].

Polyethylene glycol (PEG), a nontoxic synthetic polymer, is widely used with other natural materials to enhance their mechanical strength for cartilage tissue engineering. The studies have indicated that PEG-based hydrogel can promote chondrogenic differentiation of MSCs *in vitro* and *in vivo* [110, 111]. Injectable hydrogels used for cartilage tissue engineering have been well summarized by several review papers [112]. PEG-HA scaffold-treated patients achieved significantly higher levels of tissue fill in cartilage defects [113].


**Author details**

Amira Omrane\*, Taoufik Khalfallah and Lamia Bouzgarrou Occupational Medicine and Ergonomics Department, Public Hospital Taher Sfar, Mahdia, Tunisia

\*Address all correspondence to<EMAIL_ADDRESS>
© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Ergonomic Evaluation of Thermal Stress in a Tunisian Steel Industry DOI: http://dx.doi.org/10.5772/intechopen.98697*


**Conflict of interest**

The authors declare no conflict of interest.

*Agronomic Biofortification of Food Crops: A Sustainable Way to Boost Nutritional Security DOI: http://dx.doi.org/10.5772/intechopen.103750*


**9. β-Glucans**

Components of the cell wall of the yeast *Saccharomyces cerevisiae* have drawn interest in recent years, since their inclusion has had a positive impact on production parameters, due to their physiological effects on the intestinal digestive mucosa, by increasing the height of the jejunal villi [68]. The β-glucans are carbohydrates made of glucose polymers which provide the primary structure that is located in the wall of yeasts, fungi, algae, and cereal grains, such as oats and barley. Their structure can vary depending on the source and type of bonds present in the glucose polymers [15]. The backbone of β-glucans is formed via glucose molecules linked at carbon atoms 1 and 3 [69]. The six-sided glucose rings are connected to each other in linear or branched forms with glycosidic bonds, so the structure of these glycosidic bonds will affect the functionality of β-glucan molecules [70]. There are three structural types of these molecules: α-glucans, β-glucans, and mixed α,β-glucans. The configuration of glycosidic bonds and molecular mass are important for their characterization [71]. Fungal cell walls, which are mostly structural polysaccharides and glycoproteins, are the main source of various structural types of glucans [72].

The main biological activities attributed to medicinal mushrooms are due to the β-glucans present in their wall and in some plants. These substances are antitumor, immunomodulatory, antimicrobial, contraceptive, anti-inflammatory, prebiotic, and antioxidant [73, 74]. Supplemental β-glucans in poultry diet can enhance their innate defense by inducing intestinal colonization and invasion of internal organs by *Salmonella* [75]. The main biological properties of β-glucan (1,3/1,6) are the ability to form viscous solutions in contact with water and to form hydrogen bonds at different binding sites [76]. The β-glucan is soluble in water, although its solubility decreases with time, temperature, and pH. The highest solubility is reached at a temperature of 55°C [77]. The β-glucan has been evaluated to increase humoral response, productive performance, and viability, where an increase in serum IgA and IgG was observed [72].

## **10. Fructans**

Inulin is a natural storage polysaccharide with many applications in food and pharmacology. It can be a low-calorie substitute for sugar or fats. It is widely distributed in plants and is present in the reserve carbohydrates of just over 30,000 plant products [78]. Inulin is not a simple molecule—it is a fructan which fructose units are connected by β-bonds (1, 2). The chain lengths of these fructans range from 2 to 60 units [79]. Inulin is a storage carbohydrate in many plants. It is found in fruits and vegetables (e.g., chicory, Jerusalem artichoke, artichoke, onion, leek, garlic, asparagus, banana) and in the stem of some cereals, such as wheat, as well as agave, which has been used for the production of distilled and undistilled alcoholic beverages [80]. Many biological properties have been found in *in vitro* and *in vivo* tests with antimicrobial, antifungal, antioxidant, anti-inflammatory, antihypertensive, immunomodulatory, antiparasitic, and anticancer activity [81, 82]. An important aspect to consider is that being a material rich in different compounds of interest for agroindustry, future research aimed at the isolation, purification, and protection of agave's secondary metabolites with environmentally-friendly processes is required, in addition to thoroughly investigating the development of products based on the use of pure metabolites or their extracts, evaluation of their activity and bioactivity, as well as experiments that allow determining applications to different areas of operation [83]. Regarding the application of agave fructans in the poultry industry, so far, they have only been used as prebiotics in broiler diets to improve performance and intestinal health [15, 84]. The use of natural alternatives as antimicrobials and disinfectants is increasingly arousing interest in the consumption of safe products, as well as the interest of scientists in offering natural alternatives to prevent the transmission of pathogens through food, such as those referred to here.


**2.2.1 Size**

The size of the hand is based on an android robot which was already mentioned, EveR 3. The model of an android robot EveR 3 is Korean young woman whose height is 165cm and weight is 50kg. When humanoid robots which use real human as model are designed, they use only size like height, length of the limb etc. in general. However, android robots need more strict observation of size not only height, length of joint but also circumference of joint, each part. To make exact reference of model, the original model was scanned by 3D scanner and the scanned data was handled by 3D MAX. From this process, the data which can be used CAD program (Solid works) was earned. This data contained all information of size of original model and this can measure exactly by CAD. The size of hand from original model can be measured exactly, too. The required size data which is needed to realize same size of original model is length of each finger, length of each joint of finger, circumference of each finger, thickness of palm and length of palm. Of course, it is hard to realize exact size of each factor of original model, but this process can help to make a robot hand which is the nearest to human hand than any other existing hands. Fig. 2 shows the real size of robotic hand especially mechanical structure and comparison with real human hand whose is the designer of this hand (168cm, Korean man). Even if this man's hand is small, the robotic hand is smaller than his one. Table.1 shows parameters of main factor which are considered to design.

Fig. 2. Mechanical part of robotic hand and comparison with real human hand.

Table 1. The pamameters of developed android hand.


**4. Concluding Remarks**

Based on the AMIP-type model simulations using the Exascale Energy Earth System Model (E3SM), we investigated the changing characteristics of climate-scale (monthly) tropical extreme precipitation in a warming climate. Three ten-year-long AMIP-type model simulations were carried out: (1) a control, with the present-day SST, and CO2 atmospheric concentration, (2) P4K, the same as the control but with a forced idealized uniform 4K increase in the SST globally, and (3) 4xCO2, the same as the control but with SSTA derived from coupled model simulations under a four-times-higher atmospheric CO2 concentration, including the corresponding 4xCO2 radiative heating of the atmosphere. The key results of this study include the following:

to increased CIN, delaying the triggering of deep convection, while building up the convective available energy in the lower atmosphere associated with the warming climate. When deep convection is triggered eventually through moisture advection from episodic small-scale atmospheric eddy processes associated with land–sea breeze, thunderstorms, and orography, an explosive growth of MCS-like organization occurs preferentially over land, releasing extra amounts of convective available potential energy (CAPE) stored during CIN, and resulting in very extreme "record-breaking" precipitation over land, as global climate warming continues unabated.

The similarities in MCS extreme precipitation development over ocean and land and between 4xCO2 and P4K underscore the importance of SST warming as the primary forcing in the development of MCS-like organization, leading to extreme precipitation. However, non-uniform SSTA based on ensemble coupled models together with dynamically consistent CO2 radiative forcing of the atmosphere is needed to produce stronger and presumably more realistic regional characteristics of extreme precipitation in the warming climate of a future world through dynamical adjustments and feedback processes in the coupled atmosphere–ocean–land system. For a better understanding of the effects of CIN in staging very extreme "record-breaking" regional precipitation events over land, intrinsic land–atmosphere feedback processes and impacts by concomitant changes in the tropical large-scale circulation, land–sea contrast, and under P4K and 4xCO2, comparisons with CMIP6 model outputs, and multiple sources of precipitation and cloud observations are being investigated in our ongoing research.

Finally, we note that high-resolution MCS resolving meso-scale (10–20 km) and cloudscale (<5–10 km) models are required to conduct studies of extreme precipitation events on hourly/daily time scales over limited spatial/time domains. Cloud-scale GCM and coupled GCMs are certainly desirable for better simulations of MCS over the global domain. However, such GCM simulations are highly labor-intensive and expensive for climate-scale long-term integrations. That is why most long-term GCM climate experiments, such as in CMIP6, are still expected to run at moderate-to-low resolution (>50–100 km) in the foreseeable future. Here, we show important results indicating that improved cumulus parameterization in a state-of-the-art GCM with moderate resolution can show MCS-like organization features for extreme tropical precipitation, on monthly time scales. Such an approach allows for the physics of extreme precipitation, such as MCS-like organization, to be explored and evaluated by precipitation and cloud observations on a global climatic scale, bridging the gap between meso-scale and low-resolution climate models.

**Supplementary Materials:** The following supporting information can be downloaded at: https://www. mdpi.com/article/10.3390/atmos14060995/s1, Figure S1. Spatial distribution of SST, Frequency of Occurrence (FOC), and the fraction of stratiform (large-scale) rain for top 5% monthly precipiptation; Figure S2. Spatial distribution of SST, precipitation efficiency (PE), outgoing longwave radiation (OLR) for top 5% monthly precipitation; Table S1. Extreme tropical monthly precipitation intensity threshold (mm/day) as a function of top-percentile rain rate for the entire tropics (30◦ S–30◦ N).

**Author Contributions:** Conceptualization, W.K.M.L. and L.R.L.; methodology, W.K.M.L., B.H. and K.-M.K.; software, B.H. and K.-M.K.; validation, W.K.M.L., B.H. and K.-M.K.; formal analysis, K.-M.K.; investigation, W.K.M.L. and K.-M.K.; resources, L.R.L., B.H. and K.-M.K.; data curation, B.H. and K.-M.K.; writing—original draft preparation, W.K.M.L.; writing—review and editing, L.R.L., B.H. and K.-M.K.; visualization, K.-M.K. and W.K.M.L.; supervision, W.K.M.L.; funding acquisition, W.K.M.L. and L.R.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the U.S. Department of Energy (DOE), the Office of Science, Biological, and Environmental Research as part of the Regional and Global Model Analysis Program Area under Grant Award #300426-00001, awarded to the University of Maryland from the Pacific Northwest National Laboratory (PNNL). The PNNL is operated for the DOE by the Battelle Memorial Institute under contract DE-AC05-76RL01830. Partial support was also provided by the NASA Modeling and Analysis Program, Federal Award Identification # 80NSSC21K1800, awarded to the University of Maryland and to the NASA Goddard Space Flight Center.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data used in this research were based on model outputs of the DOE/PNNL, available at https://portal.nersc.gov/archive/home/b/beharrop/www/e3sm\_v1\_pd\_ and\_warming\_experiments/e3sm\_v1\_control\_simulations.tar (assessed on 1 June 2023).

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

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**9. Differential diagnosis**

PPCM should be differentiated from other forms of cardiomyopathy (**Figure 4**), heart failure, pulmonary thromboembolism, severe eclampsia, and pneumonia. From history, in physical examination and investigations, one must exclude myocardial infarction, idiopathic dilated cardiomyopathy, and valvular heart disease [9].

**Figure 4.** *Four chamber echocardiographic view showing thrombus in PPCM.*