## 1 Introduction  
The incidence of anterior cruciate ligament (ACL) tear ranges from 30 to 52 per 100,000 people in different countries [1; 2; 3]. It commonly occurs from a noncontact twisting injury of the knee during sports activity. Once torn, the ACL does not heal spontaneously by itself because of poor vascularization of the ruptured ligament and an unfavorable intra-articular environment [4]. Therefore, ACL reconstruction (ACLR) is the golden standard to deal with ACL tear with a success rate up to 90% [5; 6]. Plenty of graft choices are reported from literature, such as hamstring, bone-patellar tendon-bone, and quadriceps autografts and allografts. However, there is still a lack of agreement regarding the effect of graft source on the functional outcome of surgery [7]. On the other hand, there is still controversy regarding the upper age limit of ACLR. [PERSON] et al. published a systemic review describing that ACLRs in patients aged 40 years and older with functional instability could produce satisfactory results [8]. However, ACLRs in elderly donors have more comorbidity and readmission within 90 days of surgery [9]. Furthermore, cells from elderly donors have slower cell metabolism, which may be responsible for a weaker tendon-bone healing [10], leading to graft failure. In a rat model, [PERSON] et al. demonstrated that ACL-derived cells from younger donors enhanced early bone-tendon healing in an immunodeficient rat model of ACLR. Surgeons should consider a donor's age before ACLR and try to avoid any condition that jeopardizes tenocytes proliferation to achieve a high success rate of surgery. Corticosteroids are, in many cases, the primary nonsurgical option for treating painful and inflammatory musculoskeletal pathologies. However, they are associated with significant side effects and often lead to tissue degeneration [11]. The use of corticosteroids has been confirmed to reduce tendon strength and suppress proliferation and collagen synthesis of tenocytes derived from animal tendons [12; 13]. Tenocytes treated with dexamethasone, one of the commonly used corticosteroids, at a range of doses (0.1-1000 nM) decreases cell proliferation in a dose-dependent manner [14]. Dexamethasone has also been reported to induce adipogenic differentiation [15; 16; 17] and adipogenic with chondrogenic differentiation in tendon stem cells [18], which decrease the mechanical properties of the reconstructed ligament such as ACLR using hamstring tendon graft. On the other hand, [PERSON] et al. proved that dexamethasone treatment stimulated cell proliferation at lower concentrations (<1000 nM), whereas a high concentration (>1000 nM) decreased cell proliferation [19]. Therefore, the dosage of dexamethasone plays an important role in tenocytes studies. Ascorbic acid (vitamin C) is a cheap and well-characterized antioxidant known to promote collagen biosynthesis and prevent free radical formation [20]. [PERSON] et al. showed its efficacy in protecting hamstring-derived tenocytes from oxidative stress and proposed it as an additive to dexamethasone injections [21]. [PERSON] et al. proved the decrease in cytotoxic effects of anesthetics and non-steroid anti-inflammatory drugs (NSAIDs) towards tenocytes from rotator cuff tendon when treated together with ascorbic acid in a microfluidic platform [22]. However, ascorbic acid had its cytotoxicity in relative high concentration. [PERSON] et al. described that ascorbic acid was strongly toxic to cells in concentrations above 10 mM and negatively affected cell morphology at concentrations from 1 mM [23]. Therefore, the optimal dose of ascorbic acid should be determined before clinical application. There are not much data about the effects of different doses of dexamethasone and ascorbic acid when treated together in tenocytes derived from human hamstring tendon, which is commonly used for ACLR. Additionally, there are differences in cell proliferation between tenocytes from young and old donors.